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Deck Limit Mark

Posted: 09 Dec 2003, 22:40
by Chris
A small confusing item?
:cry: I have just finished putting my IOM together, but before submitting for measurement where do I put the deck limit mark as I can find no clear explaantion of where it goes other than in ule D.1.5 "on the centreplane of the hull near to the mast positon"
As I have "skiff style" lowered cockpit does this mean it goes at the level of the foredeck?
Is it a straight, horizontal line as the rule confuses me by saying "minimum of 5mm in diameter"
:wink: :mrgreen:

Posted: 10 Dec 2003, 03:53
by Steve Landeau
It's meant to be a circle, 5mm diameter. It can technically be placed anywhere in the mast step area. BUT, at the worlds last summer, my boat had the mark on the vertical bulkhead just forward of the mast. The event measurer made me move it, cause he could not accurately place a measuring tape to it. The easiest is to place it just beside the mast.

Posted: 10 Dec 2003, 04:06
by Greg Vasileff
I think the bigger question here Steve is just where it is 'supposed' to be placed. On a hull like the Italico, or an Errica, can it be either on the raised deck or where the mast enters the lower deck, or anywhere in between? We were just having this discussion at our club a couple of weeks ago.

Posted: 10 Dec 2003, 04:22
by Steve Landeau
Greg, it really does not matter where you put it, so long as it is in the origin of the mast, so you can measure from it, to your lower mast band on all rigs. Considering a skiff, If you are asking where I would put it, it would go as low as possible (in the cockpit where the mast goes into the step). Remember, if you put it at the highest point, all rig lower mast bands must be above it by 60mm (C.7.4(a)).
Lastly, if you are at all confused about this, just make all your rigs exactly the same from the mast band down (gooseneck assembly, and any extra mast below it, as they should be anyway), and your measurer can help you appy the deck mark.

Posted: 10 Dec 2003, 10:50
by awallin
Here are a few deck marks copy-pasted from my Vancouver pictures
<img src=" ... mage10.jpg">
(two cockatoos, an italiko and a gadget.)

I don't think anyone places the limit mark on the foredeck. If it's possible, people seem to place the mark on the centerline of the boat aft of the mast hole.

hope this helps.

Posted: 10 Dec 2003, 21:20
by Chris
:D Thanks for prompt replies all

Will put a dot on deck behind mast as per photos.

Xmas Cheers and beers to all from downunder

Deck Limit Marks

Posted: 14 Mar 2006, 23:13
by Graham_Snook
Now I have a date to work to (See triple crown thread in General IOM), I'm facing my measuring demons and have got to paint marks on my home made hull....the big question is where?...this thread was very helpful, but the pics are no longer embedded :(

Does anyone have a link to the photos that were in this thread?


The deck limit mark shall be displayed on the centreplane of the hull near to the mast position. It shall be a minimum of 5 mm in diameter.

How near is near?

The problem I have is that I have an 3mm thick aluminium plate which acts as a washer for my fin bolt and a spacer for my mast so I get no movement in either, and both are the right distance apart.

As I understand it the Deck Limit Mark is a 5 mm dot on the deck where the mast enters the hull. Would it be alright to drill a hole in the plate (say 6mm) so the dot is visible on the deck or would this make it hard to measure from?

Posted: 15 Mar 2006, 00:13
by Bruce Andersen
all the deck limit mark does is to define the point of origin for rig measurements, and is intended to maintain some sort of consistency between rigs (in terms of height off the deck), therefore the exact placement is not as important as making sure all your rigs measure to wherever you decide to stick it.

Posted: 20 Mar 2006, 06:22
by IanHB
Graham, I would accept a deck limit mark either directly behind your aluminium plate or beside your mast.
Its sole purpose is to specify where you want your mast height to be measured from.
In your case that would be the deck under the mast and not the raised foredeck. Yes?

Posted: 20 Mar 2006, 16:39
by Graham_Snook
IanHB wrote:I would accept a deck limit mark either directly behind your aluminium plate or beside your mast.
Many thanks for that, I wasn't too sure whether it would be "near" enough if I put the mark aft of the metal plate. But I'd hate for my Triple Crown to be illegal on a the placing of a 5mm dot :D

Posted: 14 Apr 2006, 12:27
by rémi brès
take care Graham, your main sail is going under the lower band..... :roll:

Many thanks :-)

Posted: 21 Apr 2006, 12:44
by Graham_Snook
Thanks for that I wasn't aware I was infringing the rules.

That's the problem when you're new to something, little things can easily be over looked

Just a quick question, what would be the best way to correct this?

Could I:

Move the mark down so it's still over 60mm and less than 100mm but within the 1600 from the upper mark?


Tighten up the head of the sail by shortening the main halyard

My boat has still yet to be certified - Work has picked up - so any solutions are welcome

Thanks again


Posted: 21 Apr 2006, 17:13
by rémi brès
the way I do :
the upper band is the top of the mast, (head fitting from GB is the upper band
middle band is 1 mm before the max permitted from the top
lower bans is 1 mm before the max permitted from the top
then, I cut the mast so the lower band is beetwin 60 and 100 mm from the deck point

respect the max length of the main halyard, so you can change it for another one later

deck mark

Posted: 21 Apr 2006, 20:16
by ralph kelley
I belive this is pretty straightforward. This "mark" locates the spot where the measurer checks the location of the bands on the mast, or put differently, the elevation of the sails above the "deck". The "mark" tells the measurer where you consider the deck.

With a skiff type deck and where the mast is keel stepped, assuming you want the mast low (for potentially better high wind capability) put the mark adjacent to, or right behind the mast where it enters the cockpit floor/deck. However if you want the mast high (better for light winds, I suspect), put the mark on the foredeck, on centerline. (I have not seen anyone select the foredeck for the "deck" in terms of the mast location; everyone has chosen the floor of the lower elevation cockpit.)

For craft that use a keel mounted mast and have a deck configuration popularized by the Bantock boats, put the "mark" at the very bottom of the cone, showing the measurer that you want that to be the "deck", or on the aft deck, or foredeck, if you want that higher elevation as the reference. I cannot remember anyone using anything but the bottom of the cone.

With a mast mounted on the deck (not mounted on the keel), put it adjacent to or on centerline at the deck level. The mast step plate, if used as shown in the photo above, would be included in the 60-100 band range.