Clew height v's Foot length

Use this forum to discuss the latest changes in the class
Post Reply
User avatar
MCR
Posts: 113
Joined: Tue Dec 09, 2008 11:25 pm
Location: Pittwater, Sydney Australia
Contact:

Clew height v's Foot length

Post by MCR » Mon Dec 15, 2008 2:48 am

Hi all

I'm in the unfortunate position of having to build my sail before I've started the boat due to my changing employment situation and I was after opinions on clew height v's foot length. It seems to me that everyone tacks and gybes by standing up behind the back of the boom. I'm looking at going down the una-rig route and if I go for a clew height of 800mm above the deck the boom is about 200mm longer than if I had a lower clewed main (say 300mm above deck). Would you rather have the lower clew so you didn't have to go as far back in the boat to tack or would you still prefer to have enough clearance under the boom to duck under? I've never sailed the IC's before so I don't have first hand knowledge but I've done my time in Moths and skiffs over the years.

Anything you can pass on would be appreciated. Thanks
Jethrow
AUS 33
Magic Carpet Ride
http://jethrowsicpage.blogspot.com/

H Virtue
Posts: 239
Joined: Fri Jan 02, 2004 4:34 am
Location: Australia

Re: Clew height v's Foot length

Post by H Virtue » Mon Dec 15, 2008 6:53 am

Going under v's round the back its personal choice I would guess its 50-50 but it also depends on conditions... circumstances on the water. Generally I go under around 95% of the time its only occasionaly I go round the back.

My clew is approx (make that very approx as I have never measured properly) 700mm above the deck at the centre line I wouldn't want mine any lower for going under (more so for light airs as the boom angles down as it goes forward).

Personally I would say give yourself the space to go under, sail a Canoe for a while and find out if under or around is your thing by then you will have had enought time in the boat you would be looking at a new suit of sails (due to wear and tear) and then you can make the changes to a new suit. I still have enough room to go around the back but Im in sloop mode, Phil Stevo would be the one to ask about under boom clearance/length regarding a una-rig

H.

Phil Stevenson
Posts: 202
Joined: Wed Sep 07, 2005 9:54 pm
Location: Australia

Re: Clew height v's Foot length

Post by Phil Stevenson » Tue Dec 16, 2008 7:26 am

Geoff,
The boom height on my boat ended up being based on height above water and being able to sheet out when healed slightly over without dragging the boom in the water. Foot is 2.7m long.
It was initially quite a bit lower but after watching me sail one gusty day the sailmaker cut about 6 inches off the leach and I found it much easier to sail after that. That was about when the sail became undersize as well.
I go under the boom which is now much easier too.
My sail is almost the same luff length as a moth sail (5185mm max) and only slightly longer on the leach.
Its hard to get the max area into a single sail without obvious problems:
. Sail looking squat
. the boom so low that going around the back is necessary, not enough bouyancy that far aft.
. Boom dragging in the water
Organise a test sail in January?
Phil S
Design perfection is achieved, not when there is nothing else to add but when there is nothing else which can be taken away.
http://philscanoes.blogspot.com/

User avatar
MCR
Posts: 113
Joined: Tue Dec 09, 2008 11:25 pm
Location: Pittwater, Sydney Australia
Contact:

Re: Clew height v's Foot length

Post by MCR » Tue Dec 16, 2008 10:53 am

Hi Phil & Hayden

Thanks for that

I've been doing some some modeling with both Moth's and IC's trying to make my decision. I was looking at the IC una-rig but with a push vang to get a long luff and still have some clearance at the back. Something along the lines of what we've been doing with the 18'ers, profile wise.

A test sail around the end of January would be on the cards, no promises though, I don't know how cashed up I will be. I finish my current work in January so should have some spare time on my hands in Feb. :D
Jethrow
AUS 33
Magic Carpet Ride
http://jethrowsicpage.blogspot.com/

Barry Watkin
Posts: 89
Joined: Sat Oct 07, 2006 8:37 pm
Location: United Kingdom

Re: Clew height v's Foot length

Post by Barry Watkin » Tue Dec 16, 2008 9:29 pm

Hi there a quick input from up here! You might like to give Andy Patterson an e-mail at Bloodaxe boats. I was chatting to him last week and this problem of low booms on uni rigged boats & the art of tacking them was touched on briefly. He had various ideas going on with his boat already under the knife, but it would be better or more acurate if you chatted to him direct,Regards Barry :mrgreen: XAC
BMW

Post Reply