IOM Questions and Answers (Q&A)

IOM Questions and Answers (Q&A)

What is the difference between a Q&A and a Class Rules Interpretation?

An interpretation is requested when it is not clear (to a designer, builder, measurer, class association or certification authority) how a class rule shall be interpreted. When an interpretation is issued it should be kept in mind that the interpretation is valid until the class rules are changed or for two years maximum only. The purpose of this last rule is that two years gives sufficient time to consider if the effect of the interpretation is a) desirable or b) undesirable. Depending on the decision or choice (a or b, by the IOM ICA) the class rules can be revised accordingly.

Thus, when drafting any interpretation, it should be kept in mind how the class rules should/could be revised to make the original interpretation request redundant.

It follows that, if no revised class rule can be written, there is no need to issue an interpretation. Where no interpretation is required, but only an explanation of the effect of the class rules, it follows that it would be appropriate to deal with the original request by issuing a Q&A to be published on the IOM ICA website and elsewhere as appropriate.

This is the guiding principle used by the IRSA Technical Committee and IOM ICA  when considering any question about the class rules whether it is a formal request for an interpretation or not.

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IOM Q&A – General

https://www.radiosailing.org/question-answers/iomclass (link to IRSA website)

 IOM Q&A –Hull

Is the bow bumper of a boat which meets the required 10 mm only at deck level and thinning towards the water line in accordance with IOM Class Rules?

Question:

Is the bow bumper of a boat which meets the required 10 mm only at deck level and thinning towards the water line in accordance with IOM Class Rules?

Question details:

Is the bow bumper of a boat which meets the required 10 mm only at deck level and thinning towards the water line in accordance with IOM Class Rules?

Reference to the old interpretation issued before year 2017

Interpretation 2004-IOM-3 on IOM Class Rules – edition 2003

Answers:

IOM class rule D.2.2(c)) is dealing with “the forward 10 mm of the hull”. Relevant ERS 2017-2020 rules are H.3.1 and H.3.4. According to them, longitudinal measurements such as “forward 10 mm of the hull” shall be taken parallel to the horizontal hull axis. Therefore the hull forward of a vertical plane 10 mm aft of the foremost point of the hull and at 90 deg. to the hull centreplane has to comply with IOM class rule D.2.2(c).

So, the bumper in diagram “A” is NOT legal, because part of the forward 10 mm of the hull is not made of elastomer. The bumpers of “B” and “C” are permitted, since all of the forward 10 mm of the hull is a bumper, even though in “B” this bumper thins out to 0 before it reaches the waterline.

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Question: What range of elastomers are permitted for bumpers?

Question:

What range of elastomers are permitted for bumpers?

Question details:

“Elastomeric” means “Returns to its original shape after elastic deformation”. There are many materials that act in this way and could be used as a bumper. What range of elastomers are permitted?

Reference to the old interpretation issued before year 2017

Interpretation 2003-IOM-4 on the IOM Class Rules – edition 2002

Answer:

Elastomer listed in the IOM Class Rule D.2.1(a)(7) is any material that is able to resume its original shape when a deforming force is removed.

Elastic, rubber-like substances are permitted. The class rules do not set upper or lower limits on the elasticity of elastomer. When an official measurer is of the opinion that a hull contains materials that do not comply with this class rule, he should note it on the measurement form. The Certification Authority should not issue a certificate but should ask for a sample of the material.

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Questions related to the various chainplates positions on the hull

Question:

Questions related to the various chainplates positions on the hull

Question details:

With the emergence of the new high prismatic narrow hulls with chines, the decks are becoming much narrower than traditional IOM designs. With a narrow deck, the chainplate position moves inboard and the shroud base gets narrower. I have attached pictures of a narrow IOM (see below) with rounded sides where the chainplate eye has been placed proud on the center of the topsides to widen the shroud base. See diagram F.

Question is does this contravene IOM class rule D.2.4(c) Fittings shall not project outboard of the hull shell or deck.

This question raises the issue of the location of the sheer and where the deck ends and the topsides of the hull begin. The chainplate eye can project above the deck, but cannot project outboard of the hull shell. So how do we interpret the class rule for the diagram examples B, C, D, E and F?

It also asks the question about the hull shell – is the class rule use of SHELL, referring to the plane of the hull in the area of the chainplate eye, or is it referring to max beam?

In case B, the sheer is a small radius curve and the chainplate eye extends outboard of the hull lines and max beam.

In case C, the sheer is a large radius, and the chainplate eye lies inside max beam. There may be some question as to where to locate the projection lines.

In case D, the hull bottom is round and the chine extends from a vertical tangential extension at max beam. The chainplate eye is outboard of the chine, but inside max beam.

In case E, the hull bottom is a flat section and the chine extends from a wide angle tangential extension at max beam. The chainplate eye is outboard of the chine, but inside max beam.

In case F, the hull is an oval with no discernible sheerline or chines where the chainplate eye is attached. This matches the picture of the IOM (below).

Reference to the old interpretation issued before year 2017

Interpretation 2013-IOM-1 on IOM Class Rules – edition 2013

Answers:

Relevant IOM Class Rule:

D.2.4(c) Fittings shall not project outboard of the hull shell or deck.

Relevant ERS 2017-2020 rules:

D.1.1 Hull – The hull shell including any transom, the deck including any superstructure, the internal structure including any cockpit, the fittings associated with these parts and any corrector weights.

H.3.1 –  For a boat,  unless  otherwise  specified,  words  such  as  “fore”,  “aft”,  “above”, “below”,  “height”, “depth”,  “length”,  “beam”,  “freeboard”,  “inboard”  and “outboard”  shall  be  taken  to  refer  to  the  boat  in  measurement  trim.  All measurements denoted by these, or similar words, shall be taken parallel to one of the three major axes.

Shrouds attachment points (chainplate eyes) as shown on sketch and marked with A, C, D, E and F and shown on photo are not projecting outboard of the hull shell and they are permitted by the IOM Class Rules.

Shrouds attachment points (chainplate eyes) as shown on sketch and marked with B are projecting outboard of the hull shell and therefore not permitted by the IOM Class Rules.

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Is it permitted to use fillers and gel coats containing micro baloons?

Question:

Is it permitted to use fillers and gel coats containing micro baloons?

Question details:

  1. a) Is it permitted to use fillers that contain:

– micro balloons?

– bulking materials such as slate, talc etc?

  1. b) Is it permitted to use epoxy gel coats that contain micro balloons?

Reference to the old interpretation issued before year 2017

Interpretation 2003-IOM-4 on the IOM CR – edition 2002

Answer:

YES – in adhesives, NO – in glass reinforced plastic.

Fillers are permitted provided they are constituent parts of permitted materials listed in IOM CR D.2.1. Fillers supplied as parts of a resin for laminating or/and gel coat are constituent parts of laminating resin and/or gel coat which are explicitly mentioned as parts of the glass fibre reinforced plastic. Another filler added by the builder to laminating resin and/or gel coat is not a constituent part of laminating resin and/or gel coat.

Fillers are a normal part of adhesives and therefore permitted.

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Questions related to the various materials used to build IOM hull related to the IOM Class Rule D.2.1(a)

Questions:

Questions related to the various materials used to build IOM hull related to the IOM Class Rule D.2.1(a).

Questions details:

Question No.1: Assuming the OUTSIDE was coated with opaque or translucent paint and the inside of the wooden shell is covered with glass cloth (GRP), which is then painted with clear varnish or resin, does the construction comply with the class rule D.2.1(a)?

Question No.2: Assuming the INSIDE of the wooden shell was coated with opaque or translucent paint and the outside is covered with glass cloth (GRP), which is then painted with clear varnish or resin, does the construction comply with the class rule D.2.1(a)?

Question No.3: If both INSIDE and OUTSIDE are covered with glass cloth (GRP), which is then painted with  clear varnish or resin, does the construction comply with the class rule D.2.1(a)?

Question No.4: Assuming the INSIDE of the wooden shell is coated with opaque or translucent paint and the OUTSIDE is covered with glass cloth (GRP), which is then painted with coloured varnish or resin does the construction comply with the class rule D.2.1(a)?

Question No.5: If the OUTSIDE is covered with glass cloth which is then painted with coloured varnish or resin and the INSIDE is covered with glass cloth and then painted with clear varnish or resin, does the construction comply with the class rule D.2.1(a)?

Question No.6: Does a construction of a pigmented gel coat and a un-pigmented laminating resin with the hull fibres laid up whilst the gel coat was still wet comply with D.2.1(a)?

Reference to the old interpretation issued before year 2017

Interpretation 2010-IOM-1 on the IOM CR – edition 2009

Answers:

Answers on all questions is Yes.

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Is accidentally moulded small bits are permitted in a moulded hull?

Question:

Is accidentally moulded small bits are permitted in a moulded hull?

Question details:

Is workshop dust and other accidentally moulded in small bits like insects, air bubbles, bristles, hairs etc permitted in a moulded hull?

Reference to the old interpretation issued before year 2017

Interpretation 2003-IOM-4 on the IOM CR – edition 2002

Answer:

Having in mind IOM class rule D.2.1, we may presume that it is normal to have some imperfections in mouldings and it is not necessary to explicitly mention this in the class rules. Their presence should be noted by an official measurer if he feels it appropriate. However this would not normally prevent the Certification Authority from issuing a certificate. The presence of particles of foreign materials not permitted by the class rules but reported on a measurement form would not be a reason for the certification authority to decline to issue a certificate.

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Is it permitted to use standard servo casings?

Question:

Is it permitted to use standard servo casings?

Question details:

Is it permitted to use standard servo casings to enclose/support remote control equipment as these ‘containers’ (as stated in the preamble of the IOM Class Rule D.2.1 (a)) are made with unknown fillers?

Reference to the old interpretation issued before year 2017

Interpretation 2003-IOM-4 on the IOM CR – edition 2002

Answer:

The casing is an integral part of the control unit. The materials used in remote control equipment are not restricted.

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Is sticky cloth deck patch material permitted?

Question:

Is sticky cloth deck patch material permitted?

Question details:

The usual sticky cloth deck patch material is a dacron/terylene woven cloth coated with adhesive. Is this a film covering material? Is Dacron/terylene a permitted fibre reinforcement for this special case?

If so, are other fibres such as carbon, kevlar, which like polyester fibre, are not permitted as part of a

GRP plastic permitted as part of a film covering material?

Reference to the old interpretation issued before year 2017

Interpretation 2003-IOM-4 on the IOM CR – edition 2002

Answer:

Sticky cloth deck patch material made of dacron/terylene woven cloth coated with adhesive is a polyester fibre reinforced film covering material as permitted by IOM Class Rule D.2.1(a)(6).

Carbon and Kevlar fibres and alike in deck patch material are prohibited because they are not “polyester fibres”.

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Is it permitted to use a “Texalium” in the IOM moulding hulls?

Question:

Is it permitted to use a “Texalium” in the IOM moulding hulls?”

Question details:

Is it permitted to use a “Texalium” in the IOM moulding hulls?”

Reference to the old interpretation issued before year 2017

Interpretation 2004-IOM-4 on IOM Class Rules – edition 2003

Answers:

“Texalium” is a woven, aluminium coated, glass fibre, epoxy prepeg (or not) product. Aluminium is applied on one side through a special treatment (sublimation and re-condensation in a vacuum, in a 0.025 µm thick coat) and needs the use of a specific “coupling agent” which allows good mechanical behaviour. Aluminium coat has an aesthetics function. Physical and mechanical properties of Texalium are consistent with that of a plain glass fibre reinforced plastic.

Glass fibre reinforced plastic (GFRP) excludes everything except glass fibre reinforcement and laminating resin as defined by the IOM class rule D.2.1(a)(3).

“Texalium” has internal metal content and “coupling agent” which contravene IOM class rule D.2.1(a)(3) and it is not permitted to use it in the IOM moulding hulls.

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Are “pellettised” thermoplastics with unknown additives permitted?

Question:

Are “pellettised” thermoplastics with unknown additives permitted?

Question details:

“Thermoplastic” mentioned in IOM Class Rule D.2.1(a)(8) means “Softens when heated, re-hardens on cooling”. It is assumed that the rule permits vacuum formed hulls made from ABS PVC etc. but does it permit more materials?  Are “pellettised” thermoplastics with unknown additives permitted?

Reference to the old interpretation issued before year 2017

Interpretation 2003-IOM-4 on the IOM CR – edition 2002

Answer:

Pelletised thermoplastics are allowed for the construction of the hull if they are in the compliance with the IOM class rule D.2.1(8) i.e. if containing only permitted materials

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IOM Q&A  – Hull Appendage

Questions related to the various rudder arrangements

Questions:

Questions related to the various rudder arrangements

Questions details:

In the IOM class

  1. is it permissible to build a rudder with one or more (approximately) horizontal foils on the (approximately) vertical blade?
  2. Is it permissible to build a rudder on a single shaft that has more than one blade, each inclined at a different angle to the central vertical plane?

Reference to the old interpretation issued before year 2017

Interpretation 2011- IOM-1(a) on the IOM CR – editions 2009 and 2011

Answers:

Part II of the IOM Class Rules (including Section E – Hull Appendages) is closed class rules defined in the ERS as “class rules where anything not specifically permitted by the class rules is prohibited”. According to the ERS 2017-2020 E.1.1, hull appendage may be attached to the hull shell or another hull appendage.  Foil is listed in ERS E.1.2(m) as hull appendage attached to the rudder.

One or more (approximately) horizontal foils attached to the (approximately) vertical rudder blade are additional items, not specifically permitted by the IOM Class Rules and therefore not permitted.

A rudder on a single shaft that has more than one blade, each inclined at a different angle to the central vertical plane is not specifically permitted by the IOM Class Rules and therefore not permitted.

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IOM Q&A  – Rig

Is a "belt drive sheet control line/unit" permitted to be used on an IOM class boat?

Question:

Is a “belt drive sheet control line/unit” permitted to be used on an IOM class boat?

Question details:

RMG Sailwinch has commenced production of a “belt drive sheet control line/unit” consisting of drum winch and sheet control line which runs along the deck (or below deck) and runs between the winch and any return pulleys. Is this belt drive unit permitted to be used on an IOM class boat?

Reference to the old interpretation issued before year 2017

Interpretation 2004-IOM-5 on IOM Class Rules – edition 2003

Answers:

IOM class rule C.7.6(a) concerns running rigging and indicates that the mainsail and the headsail sheets may be worked by a sheet control line attached to the sheet control unit.

IOM Class Rule F.6.1 indicates that materials of running rigging are unrestricted.

“Belt drive sheet control line/unit” as described by RMG Sailwinch is a type of sheet control line and it is permitted to be used on an IOM class boat.

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Is it permitted to have headsail swivel inside the watertight tube?

Question:

Is it permitted to have headsail swivel inside the watertight tube?

Question details:

Is it permitted to use headsail swivel made of a cord attached inside the watertight tube connecting bottom of the hull and deck and passing through the tube up to the deck level where it is attached to the headsail boom?

Reference to the old interpretation issued before year 2017

Interpretation 2003-IOM-1 on the IOM CR – edition 2002

Answer:

The IOM Class Rule (edition 2017) C.7.5 has requirements regarding the attachment point and alignment control of the swivel.

The deck is not a term defined in the Equipment Rule of Sailing. The ERS definition of the hull includes the deck among the other parts.  It is not the purpose of rule C.7.5 to control the deck shape which may be a complex shape in either fore and aft or transverse directions especially in unmanned radio controlled boats. Thus the swivel may be attached to a point on the surface of the deck which may be lower or higher than the surrounding deck surface. Such a deck arrangement in the region of the swivel attachment point may include a recess in the deck, inverse camber, a tube or other complex shapes.

The fact that cord may touch the tube and thus change the direction of the cord is not against the requirement that the alignment of the swivel shall be controlled only by the rigging tension. The geometry of the deck or the attachment point may affect the alignment but this does not mean “controlling” as stated in class rule C.7.5.

As a result of above, a headsail swivel attached at any height inside a tube which is connected to the deck approximately on the hull centreplane is in compliance with class rule C.7.5.

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Are the U-shaped nails driven into a wooden mast as attachments for the mainsail luff to the mast in accordance with IOM Class Rules?

Question:

Are the U-shaped nails driven into a wooden mast as attachments for the mainsail luff to the mast in accordance with IOM Class Rules?

Question details:

Are the U-shaped nails driven into a wooden mast as attachments for the mainsail luff to the mast in accordance with IOM Class Rules?

Reference to the old interpretation issued before year 2017

Interpretation 2004-IOM-3 on IOM Class Rules – edition 2003

Answers:

IOM class rule F.3.3(b)(6) states that the mast spar ring and/or loop are optional fittings used to attach mainsail luff to the spar. Loop means a piece of non rigid material passed around the mast and carrying out the same function as a ring. These two items must be able to move freely. Class Rule F.3.3(b)(7) states that the mainsail jackstay fittings are optional mast fittings.

U-shaped nails driven into a mast to attach mainsail luff to the spar are not optional fittings as described by closed IOM Class Rules. U-shaped nails or staples are permitted if they are used to attach a jackstay.

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Is it permitted to tension a jackstay/luffline of an IOM mast enough to hold a pre-bent mast straight?

Question:

Is it permitted to tension a jackstay/luffline of an IOM mast enough to hold a pre-bent mast straight?

Question details:

Is it permitted to tension a jackstay/luffline of an IOM mast enough to hold a pre-bent mast straight?

Reference to the old interpretation issued before year 2017

Interpretation 2004-IOM-1 on the IOM CR – edition 2003

Answer:

The mast spar jackstay is defined as standing rigging by IOM class rule F.5.2(b)(3). Length and tension of rigging may be adjustable unless otherwise restricted as stated in IOM class rule F.2.4(b). The function of items shall be limited to what is normally provided by items of their type as stated in IOM class rule F.2.3. The normal function of the jackstay is to fasten mainsail to the mast and jackstay must be engineered accordingly.

The mast jackstay needs to be tensioned/adjusted in order to fasten mainsail to and this tension may contribute to bending/straightening the mast.

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Questions related to the various mainsail boom kicking strap arrangements

Questions:

Questions related to the various mainsail boom kicking strap arrangements

Questions details:

Which of the following rig arrangements are permitted?

Case 1:The kicking strap is not adjustable and is fixed at each end. The forward end of the main boom is moved (up & down or fore & aft) using a fitting that is:

a) combined with the gooseneck fitting or

b)in addition to the gooseneck fitting

Case 2: The kicking strap passes through the boom and is adjusted in a fore & aft direction at the aft end of the main boom by using a fitting that is:b) in addition to the gooseneck fitting.

a) combined with the clew fitting or

b) in addition to the clew

Case 3:  The kicking strap is not adjustable and is fixed at each end. The forward end of the boom is not adjustable on the gooseneck in any direction except for rotation. The clew of the mainsail is adjustable vertically by using a line that is:

  1. a) combined with the clew fitting or
  2. b) in addition to the clew

 

Case 4:  The kicking strap is not adjustable and is fixed at each end. The forward end of the boom is not adjustable on the gooseneck in any direction except for rotation. The rotational axis of the gooseneck is adjustable by:

  1. a) rotation or
  2. b) in vertical position with respect to the mast.

Case 5:               As case 1 except that the kicking strap is adjustable.

Case 6:               As case 3 except that the kicking strap is adjustable.

Case 7:   As case 4 except that the kicking strap is adjustable.

Reference to the old interpretation issued before year 2017

Interpretation 2012- IOM-1 on the IOM CR – edition 2011

Answers:

In all answers it is assumed that kicking strap, as part of running rigging, is capable to work in tension only.

Case 1(a)

The IOM Class Rules do not specifically permit a special fitting to adjust the forward end of the boom up and down, or fore and aft. This arrangement is therefore prohibited. IOM Class Rule F.2.4(b) however permits the gooseneck to be adjusted and there are no restrictions as to the directions.

Case 1(b)

The IOM Class Rules do not specifically permit such an “additional fitting”. This arrangement is therefore prohibited.

Case 2(a)

IOM Class Rule F.4.3(a)(3) requires a kicking strap fitting, IOM Class Rule F.4.3(a)(1) requires mainsail clew fitting(s) and IOM Class Rule F.2.4(a) allows fittings to be combined. This arrangement is therefore permitted.

Case 2(b)

IOM Class Rule F.4.3(a)(3) requires a kicking strap fitting. This arrangement is therefore permitted.

Case 3(a)

IOM Class Rule F.4.3(a)(1) require mainsail clew fitting(s), IOM Class Rule F.6.2(b)(2) permits a mainsail clew line and IOM Class Rule F.2.4(a) permits fittings and control lines to be combined. This arrangement is therefore permitted.

Case 3(b)

IOM Class Rule F.4.3(a)(1) require mainsail clew fitting(s) and IOM Class Rule F.6.2(b)(2) permits a mainsail clew line. This arrangement is therefore permitted.

Case 4(a)

IOM Class Rule F.2.4(b) permits fittings to be adjusted and there are no restrictions as to the directions. This arrangement is therefore permitted.

Case 4(b)

IOM Class Rule F.2.4(b) permits fittings to be adjusted and there are no restrictions as to the directions. This arrangement is therefore permitted.

Case 5

IOM Class Rule F.2.4(b) permits an adjustable kicking strap. The Case 1 interpretations apply to the “additional fitting”.

Case 6

IOM Class Rule F.2.4(b) permits an adjustable kicking strap. The Case 3 interpretations apply to the boom fitting(s) and the line.

Case 7

IOM Class Rule F.2.4(b) permits an adjustable kicking strap.

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Questions related to the various headsail boom topping lift restraint line(s) arrangements

Questions:

Questions related to the various headsail boom topping lift restraint line(s) arrangements

Questions details:

Are devices in following examples permitted?

Question 1

A device of type 1 is shown in Diagram1 being a loop which may be attached to the topping lift and/or the headsail stay.

Alternatively it may be a loop formed in the topping lift itself when the latter is made from cord, when it may be considered part of the topping lift.

Question 2

Diagram 2 shows an elastic line of type 2 which tensions the topping lift when the boom rises in a gust.

At one end it is attached to the topping lift and at the other is attached to the boom or a fitting on the boom.

A variation has it attached to the topping lift, passing through an eye on the end of the boom then passing forward to be attached to the boom as shown by the dotted line.

 

Question 3

Diagram 3 shows a basic topping lift extended by a loop of cord which passes through an eye on the end of the boom and a further extension by an elastic line which is attached to the boom.

A ball on the end of the loop permits the topping lift to raise the boom as required, while the elastic line pulls the loop through the eye to take up the slack in a gust.

Question 4

Diagram 4 shows a loop attached to the headsail and passing around the topping lift.

A variation has the loop passing around the headsail and attached to the topping lift.

Both are of type 2

 

Question 5

Is it permitted to have any combination of two or more of the various types of line shown in diagrams 1 to 4 ?

Reference to the old interpretation issued before year 2017

Emergency IOM Class Rule changes made after Interpretation 2014-IOM-3 on IOM Class Rules 2013 has been published

Answers:

All presented devices/arrangements are permitted by the IOM Class Rules F6.2(b)(8) which permit use of one or more headsail boom topping lift restraint lines. IOM Class Rule C.7.6(c) describe the way of attachment and passing around other parts of rig and headsail

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Is the size of the rotating part of the mainsail halyard fitting listed in the IOM Class rule F.3.3(c)(1) limited in any way?

Question:

Is the size of the rotating part of the mainsail halyard fitting listed in the IOM Class rule F.3.3(c)(1) limited in any way?

Question details:

Is the size of the rotating part of the mainsail halyard fitting listed in the IOM Class rule F.3.3(c)(1) limited in any way?

Reference to the old interpretation issued before year 2017

Interpretation 2003-IOM-4 on the IOM CR – edition 2002

Answer:

IOM class rules F.2.3 and F.2.4 (a) restricts the size of the fittings.

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Is it permitted to fit a boat with more than one ‘sheet control line’?.Is it permitted to work the mainsail sheet and headsail sheet with more than one sheet control line?

Question:

Is it permitted to fit a boat with more than one ‘sheet control line’?

Is it permitted to work the mainsail sheet and headsail sheet with more than one sheet control line?

 

Question details:

Is it permitted to fit a boat with more than one ‘sheet control line’?

With the use of lever arm winches, the question has been raised about the use of two sheet control lines. These are two lines, one from each end of the arm, each with its own control elastic, to which the mainsail sheet and headsail sheet are attached.

 

Is it permitted to work the mainsail sheet and headsail sheet with more than one sheet control line?

 

Reference to the old interpretation issued before year 2017

Interpretation 2003-IOM-3 on the IOM CR – edition 2002

Interpretation 2003-IOM-4 on the IOM CR – edition 2002

 

Answer:

In the IOM class rules C.7.6(a) and F.6.2(b)(9) the term “sheet control line” is used in the singular so only one sheet control line may be used. It is important to make a distinction between sheet control line, mainsail sheet and headsail sheet.

Sheet control line is optional part of the running rigging and it is permitted to attach the mainsail sheet and headsail sheet directly to the lever arm winch without the sheet control line.

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Questions related to the various shroud attachment points on the mast

Questions:

Questions related to the various shroud attachment points on the mast

Questions details:

Question A:

Is it permitted to have a fitting in the form of a ring which goes closely round the mast and both shrouds and which may be adjusted vertically between the shroud attachment fitting and the spreaders (if used)?

Question B:

Is it permitted to have a fitting in the form of a ring which goes closely round the mast and both shrouds and which is fixed at some point between the shroud attachment fitting and the spreaders (if used)?

Question C:

If neither A nor B is permitted, is it permitted to use alternative shroud attachment points during an event?

Question D:

If shroud fittings are used, is it permitted to have openings for shrouds also (and vice versa)?

Reference to the old interpretation issued before year 2017

Interpretation 2011- IOM-2 on the IOM CR – editions 2009

Answers:

Answer to question A:

It is permitted to have a fitting in the form of a ring which goes closely round the mast and both shrouds and which may be adjusted vertically between the shroud attachment fitting and the spreaders (if used). Such ring would be considered as one of shroud fittings permitted in IOM class rule F.3.3(a)(2). Adjustment is permitted in accordance with IOM class rule F.2.4(b).

Answer to question B:

It is permitted to have a fitting in the form of a ring which goes closely round the mast and both shrouds and which is fixed at some point between the shroud attachment fitting and the spreaders (if used). Such ring would be considered as one of shroud fittings permitted by IOM class rule F.3.3(a)(2).

Answer to question C:

It is permitted to use alternative shroud attachment points during an event. IOM CR F.3.3(a)(2) allows the use of shroud openings and IOM CR F.2.4(b) permits adjustments to position of parts.

Answer to question D:

If shroud fittings are used, it is permitted to have openings for shrouds also (and vice versa). Shroud fittings and opening are permitted by IOM CR F.3.3(a)(2).

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A strut normally works in compression so is one that acts in tension compliant with IOM class rule F3.3(b)(9)

Question:

A strut normally works in compression so is one that acts in tension compliant with IOM class rule F3.3(b)(9)?

Question details:

A strut normally works in compression so is one that acts in tension compliant with IOM class rule F3.3(b)(9)?

Reference to the old interpretation issued before year 2017

Interpretation 2003-IOM-4 on the IOM CR – edition 2002

Answer:

A mast strut listed in the IOM class rule F.3.3(b)(9) is not part of rigging. It is fitting so it is allowed to work in compression as well as in tension.

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Questions related to the headsail boom swivel arrangements.

Question:

Questions related to the headsail boom swivel arrangements.

Question details:

  1. The most simple headsail boom swivel is a piece of cord attached by way of simple knot to the headsail boom. A hook at the other end of the cord is used to attach the swivel to the deck. Is the above said equipment in accordance with the class rules?
  2. Is the headsail swivel with ball race – SAILS Etc item 120d in accordance with the class rules bearing in mind that the headsail boom swivel is a mandatory part of the standing rigging?
  3. In the case where a piece of cord is attached to the bottom of a tube connecting the deck and the hull bottom is it permitted to have the mandatory boom swivel detachable at the headsail boom allowing the headsail boom swivel to remain secured to the hull only?

Reference to the old interpretation issued before year 2017

Interpretation 2004-IOM-2 on the IOM CR – edition 2003

Answers:

  1. According to the IOM class rule F.4.4(a)(3), swivel and its fitting(s) are mandatory items of headsail boom Term “fittings” is not defined by the ERS. In the above mentioned equipment the cord acts as the swivel and the knot securing the swivel to the headsail boom is acting as a fitting. A piece of cord attached by means of simple knot to the headsail boom is in the compliance with the class rules.
  1. Headsail boom swivel is mandatory item of standing rigging according to the IOM class rule F.5.2(a)(3) rule. The ball raced headsail swivel is engineered in order to work only in tension and complies with the definition of rigging given by ERS 2017-2020 1.6. Headsail swivel with ball race – SAILS Etc item 120d is in accordance with the class rules.
  1. According to the IOM class rule F.4.4(a)(3), headsail boom swivel secured to the hull only and detachable at the headsail boom is permitted.
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Is it permitted to use stainless steel rigging (including steel mast spar jackstay) as stated in the IOM class rule F.5.1 having in mind ERS defined term rigging?

Question:

Is it permitted to use stainless steel rigging (including steel mast spar jackstay) as stated in the IOM class rule F.5.1 having in mind ERS defined term rigging?

Question details:

The ERS 2017-2020 F.1.6 defines rigging as “Any equipment attached at one or both ends to spars, sails or other rigging and capable of working in tension only. Includes associated fittings which are not permanently fixed to a hull, spar or spreader.”  Where rigging is bent round a terminating hook and then round itself, this rigging is clearly not acting in tension only. Is it permitted to use stainless steel rigging as stated in the IOM class rule F.5.1 having in mind ERS defined term rigging?

Reference to the old interpretation issued before year 2017

Interpretation 2003-IOM-4 on the IOM CR – edition 2002

Answer:

Parts of rigging can work in compression and bending (which is part in tension and part in compression) as well as in shear and torsion. The ERS definition of rigging is referred to the whole piece of rigging i.e. (shroud, forestay, backstay) which shall be capable of working in tension only.

It is obvious that the whole length of a shroud, backstay or forestay is not capable of working in compression and this fact is important regarding the ERS definition. The fact that a particular short part of the rigging may work under compression also is irrelevant for this purpose.

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IOM Q&A – Sails

Is it permitted to use metal eyelets for openings on the mainsail luff? Is there a restriction on the location of any of these eyelets?

Question:

Is it permitted to use metal eyelets for openings on the mainsail luff?  Is there a restriction on the location of any of these eyelets?

Question details:

Cringles are limited to four in total in the IOM class rules G.3.1(b)(2) & (3), but luff openings for mast spar rings and/or loops for mast spar jackstay fittings are not limited in the IOM class rule G.3.1(b)(4) . Is it permitted to use metal eyelets for some or all of these openings?  Also is there a restriction on the location of any of these eyelets?

Reference to the old interpretation issued before year 2017

Interpretation 2003-IOM-4 on the IOM CR – edition 2002

Answer:

It is permitted to use metal eyelets to form luff fittings for mast spar rings and/or loops and/or for a mast spar jackstay. Their position is restricted to the luff as defined in the ERS.

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How shall a seam be checked for compliance with class rules G.3.2(a)(1) or G.4.2(a)(1)?

Question:

How shall a seam be checked for compliance with class rules G.3.2(a)(1) or G.4.2(a)(1)?

Question details:

How shall a seam be checked for compliance with class rules G.3.1(a)3 or G.4.1(a)3?

Reference to the old interpretation issued before year 2017

Interpretation 2003-IOM-5 on the IOM CR – edition 2002

Answer:

IOM class rules G.3.2(a)(1) and G.4.2(a)(1) describes the seams which, if used, shall connect the luff and leech. The seam is defined in the ERS 2017-2020 G.1.4(h). If a straight line connects the edge of the seam where it intersects the luff with the same edge of the seam where it intersects the leech, the right angle distance between this line and any point along the relevant edge of the seam shall not exceed 10 mm. Cutouts in the part/parts of the body of the sail used to shape the sail are not seams and therefore this method is not a permitted construction technique.

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Are the sail panels made of two different ply – translucent and the same one with white pigment added in compliance with G.3.1(a)(2) and G.4.1(a)(2)?

Question:

Are the sail panels made of two different ply – translucent and the same one with white pigment added in compliance with G.3.1(a)(2) and G.4.1(a)(2)?

Question details:

The sails shown in the photo were submitted for measurement.

The manufacturer of these sails considers that all the sail panels are of the same ply and the white panels are the same ply with pigment added.

An interpretation or explanation of G.3.1(a)(2) and G.4.1(a)(2) with respect to these sails is requested.

 

Answer:

According to the ERS G.1.4 (b) Ply is a sheet of sail material.

According to the IOM Class Rules G.3.1(a)(2) and G.4.1(a)(2) the body of the sail shall consist of the same ply throughout.

So, a same sheet of sail material must be used for the construction of an IOM sail. The sail material from the same roll/batch shall be used for a construction of a sailSails on photo attached to the request for interpretation/explanation are made of two different ply. Sail panels made of ply of different colours, weight, surface finish and pattern are not the “same ply” as requested by the IOM Class Rules G.3.1(a)(2) and G.4.1(a)(2) and therefore not permitted.

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