Mast Mount

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FrankJohns
Posts: 1
Joined: 31 Jul 2014, 16:22
Club: Newquay Model Boat Club
Design: Mallard

Mast Mount

Post by FrankJohns » 24 Aug 2017, 17:37

Hi All
I have acquired a rather non-descript part-built hull and it will be easier if I deck mount the mast. I realise that such mounting will eliminate the possibility of using a mast ram.
I am not looking to set the world alight with this boat but just to perform 'respectably' on our very flukey-wind lake.
Comments appreciated.
Cheers
Frank

Hiljoball
Posts: 263
Joined: 06 Jan 2006, 01:47
Sail number: CAN 307
Design: V8
Location: CAN

Re: Mast Mount

Post by Hiljoball » 30 Aug 2017, 19:44

Hi Frank,
A mast ram is a really important fitting on a modern IOM. Not only does the ram control bend in the lower half of the mast, it resists the forward force of the boom/gooseneck. If the boom/gooseneck is allowed to push froward, the boom rises and the twist in the upper main opens - this happens in gusts and loses drive. Resisting the boom/goosneck with the ram limits the forward movement and hold the trim of the entire mainsail.

The easy way to install a mast ram is by having a raised foredeck.

Or use check stays - allowed up to 100mm above the mast base.

Another way would be to have a keel stepped mast in a watertight tube up to the deck. You could then use a wedge at the deck to control lower bend.

However if you want to do a flush deck, then you may want to go to a half inch (12.7mm). This mast is much stiffer than the 11mm masts and will be easier to control when a ram is not available.

John
John Ball
CRYA #895
IOM CAN 307 V8

David Alston
Posts: 3
Joined: 18 Nov 2016, 00:19
Sail number: 11
Club: Bournville
Design: V9

Re: Mast Mount

Post by David Alston » 31 Aug 2017, 09:35

CHECK STAYs

If you really want to step the mast on the deck you might consider using CHECK STAYs to control the lower portion of the MAST. The Class Rules still allow for this and limit the height of the CHECK STAYS hound point to 100mm above the HEEL of the MAST i.e. the MAST Step.

You will have to attach the CHAIN PLATE to the hull about 20 ..25mm aft of the MAST to render the CHECH STAY effective in restraining the mast movement.

However ... IOM Class moved away from this many years ago for good reason. Its a pain in the stern....but the option to utilise CHECK STAY(s) was never removed from the CLASS RULES.

References:-
International One Metre Class Rules 2017

F3.3(b)10
F3.4
F5.2(b)1

The Equipment Rules of Sailing for 2017-2020
F1.7(b) iv

This arrangement is not likely handicap you too severely in light to moderate air but MAY be difficult to find the correct setting when the wind freshens particularly as you will need to adjust the port and starboard CHECK STAY independently.


Semi FIXED MAST BLOCK

You MIGHT consider employing a semi FIXED MAST BLOCKING arrangement using a cover plate on the deck and stepping the MAST on the Hog. This removes the necessity of fabricating a MAST BOX. This will necessitate the MAST being reinforced up to the LOWER MAST BAND in order to get the desired effect i.e. glue a bit of hard wood inside the MAST.

MAST RAM

The MAST STRUT / RAM is a single point adjustment but does require the MAST to be stepped on the hog of the hull and so required a MAST BOX to control the ingress of water and to restrict the LATERAL movement of the MAST.

One sincerely believes that the time spent in fabricating a MAST BOX in order to install a MAST RAM is well justified in the long term and DOES NOT REQUIRE a STEPPED / RAISED FORDECK DECK arrangement as is intimated in the previous posting. This will also necessitate the MAST being reinforced up to the LOWER MAST BAND if the FLAT deck arrangement is employed in order to get the desired effect i.e. glue a smaller tube or hard WOOD inside the MAST.

There are thousand solutions to any one problem, best is to sketch it, think about it, sketch it again then implement it.

I see your eyes getting glazed over and all you want to do is go sailing

Summer is almost gone - get sketching

Dave

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