Loose footed sail problem

Re: You can keep your assumption, Charles

Racing boat or cruising boat is irrelevany IMO and we have a cruiser racer with a big sail area and therefore big loads.

<<Your reefing point is true, but bear in mind the pressure is then being taken by a line going round a pulley wheel and through the boom, not a strong vertical force being exerted between metal on metal (in the case of the slug).>>

Not sure that is correct since the outhaul is also a line going round a pulley and through the boom. If however there is a significant vertical component to that force then that is perhaps where the load comes on the metal slug (unreefed) or on the wraparound loop of the reefline (reefed).

The velcro or webbing loop has merit as being capable of some slack in the fit to allow the outhaul to be eased, whereas the reefline wraparound attachment might pull taught and cause some friction.

I'm off to the boat now to do some jobs but I 'll take the opportunity to buttonhole some of our race fleet guys as well for what they do, they are out today I know.

Thanks, this is very much food for thought!

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Quick Racer Survey

Hi Salty

Well I managed a small survey. Of the 5 medium sized race boats I questioned that had loose footed mains, all had the metal clew slug/slide and none had additional reinforcement like webbing straps etc. At first glance it seems that it is not really necessary and people I spoke to said perhaps it was the boom section that was defective. Then the last boat I questioned said they were offered a web strap with their new sail but declined it, but also said that their sailmaker who has the same type of boat and same laminated mainsail HAD fitted one on his boat!

I will ask my sailmaker's opinion and if I smell even a whiff of doubt will have him supply the boom strap as well.

Thanks again, Robin.

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Doesn\'t maths say ????

As the clew moves towards the mast - the boom must droop ... albeit a slight amount .... as you cannot change the length of leech. Simple triangular maths ??

Not trying to be smart - just confused......

Seems the problem is not so much the foot / clew - but leech length .... being too long !



<hr width=100% size=1>Nigel ...
Bilge Keelers get up further ! I came - cos they said was FREE Guinness !
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On my conventionally bermudian rigged 26 fter the boom was at a height which was exactly right to brain me as it went over... just above eye level, where I might not see it. THe sailmaker (Jekells) made my new main with what they called a 'kick' - same sized in every dimension, except the leech arranged in such a way that the boom came across at 6'4"... leaving a couple of inches to spare. Of course it does lead to a few hat overboard situations, but that's another matter

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Thanks ......

My faith in SB is not so lost then ..... makes a change for someone to side with me !!!!

So how much do I owe you ????


<hr width=100% size=1>Nigel ...
Bilge Keelers get up further ! I came - cos they said was FREE Guinness !
/forums/images/icons/cool.gif
 
Our boom is clear above head height and only just comes aft of the sprayhood, with traveller & mainsheet on the coachroof, pretty safe. SWMBO however has hit her head umpteen times on the boom end when climbing out on the sidedeck! Rest assured therefore that it is just a question of time before it gets you again....

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Hi Robin,
Well I know what you mean. I don't mind if it's safe or dangerous. It's the 'might sometimes be dangerous' that catches you out! Clunk.

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Re: Vivid imagination

As I use my kicker and topping lift to attempt to change the shape of my main all the time, I would say yes it does make a difference why should'nt it the sail is attached to the boom at both ends.
Mike

<hr width=100% size=1>www.sailingforfun.co.uk
 
No problem at all

I have never been hit by the boom - which I cannot see - so obvious answer - put a roof over your head. - think of all that extra windage for down wind work.

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iMPOSSIBLE

As you know I love your boat and especially being indoors for winter sailing in such charming company. However, I couldn't have a boat like that a) because I'm not as rich as you and the mooring fees would leave my children homeless and b)I couldn't put up with all the Blackwater sarcasm...'have you had any good cucumbers out of that yet, then?' I'll stick with my 26 foot bum-freezer

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Sorry to have caused annoyance

But there had to be other factors as well as sheer pressure of weather to have caused the catastrophic failure you cite.

Perhaps the slug was undersized, perhaps too much tension was put on the mainsheet, or the wrong boom section had been specified, but I would still maintain (as do the sparmakers I've spoken with) that the probability of such a failure is <1% and far from commonplace.

The fact that I've had a mast fatigue fail right round the section and start its second circuit doesn't mean it's likely to happen to everyone else.

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Re: Quick Racer Survey

To add to your survey...

All 3 of my boats have had loose footed mains with the clew held to the boom.

My 7m Extravert had a single metal slug.

My 10m X99 had a double metal slug. There are a lot of X99s all the same.

My Dragonfly has got a small length of track with a ball bearing car (like a Genoa track/car).

I'm not commenting on what is suitable - just adding to the survey.

<hr width=100% size=1>One day, I hope to own a real boat.
 
I believe the ideal solution to your problem already exists on many Hallspars alloy booms. The upper surface of the outer boom end is a welded in flat plate on which a short "T" track is mounted. The mainsail is tack is shackled to a slider on this track as is the outhaul. This solves all the strength worries while retaining good foot tension adjustment with the outhaul.

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Sailmaker\'s Update

As I said I have a vested interest in this since I have a new loose footed mainsail on order. There are many factors involved and my friendly sailmaker was kind enough to give me the unexpurgated version but basically there are some key points:-

1. It depends on whether you have a big boat or a small one.

2. It depends on the kind of sail material used (stretchy Dacron v non-stretchy laminate)

3. It depends on the mainsail control gear power available (kicker, mainsheet and outhaul power)

4. It depends on how hard it is used (crew of gorillas on the rail or wifey making coffee below)

5. It depends on the sail slide material (plastic or metal or track/roller car)


So if you have a high load combination, ie biggish boat, laminated sails that stretch little, big sail, rail sitting gorillas, low stretch boom end mainsheet, low stretch high power kicker then you need a webbing strop or a track/roller car system. The webbing needs to be less stretchy than the sail so spectra or similar, and it needs to be tight or the slide/slug will pop out anyway, albeit the clew will still be kept close to the boom.

If however you have a smaller boat with a plain Dacron sail a metal slug/slide alone should be fine. Plastic ones have been fitted by some sailmakers for less friction but can deform enough to pop out of the track.

So for our 41ft boat with a tri-radial Hydranet spectra reinforced sail the message was that the metal slug/slide was probably OK, any bigger than 41ft might need a track/car. BUT if the mainsheet was moved from the coachroof to the boom end and changed for a Dyneema one, plus SWMBO sat out on the rail (what odds on that I wonder) then we should add a strop or better still but expensive a short track/ roller car system. My idea of reeving the clew outhaul line around the boom as is done for all the reef lines would work but friction would stop any adjustment. With a Spectra strop wound round several times and velcro fastened, this would be belt and braces but we would have to release it in order to adjust the clew.

Another question has just come to mind is what would happen in strongish winds if the clew outhaul line slipped free, ours is just held on a jammer on the inner end of the boom. I suspect the slug would pop out very easily. Memo to skipper - cleat off outhaul somehow to back up the jammer?

So there you have it, horses for (race) courses maybe, but thanks to Salty for raising the question, I have added a spectra strop to our order!

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I'd agree - we have a loose footed fully battened sail, and the clew is shackled to a short length of roller bearing track. Apart from holding the clew close to the boom, it ensures that the clew outhaul always has a fair lead to the sheave at the boom end. This way the clew outhaul acts as desired (hauling the clew out), not as a leach downhaul (for which it isnt designed).

No doubt in this day and age, a piece of spectra webbing will do, but it may hold the clew as close to the boom whilst still allowing it to slide in and out. Could also be bad news if you have a painted boom.

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The old man's Westerly Storm has Kemp spars, and the clew shackles onto a car with ballbearing wheels which fits inside the bolt rope groove in the boom. The car is then pulled out along the boom by a 6:1 tackle.

cheers,
david

<hr width=100% size=1>I employed you people to get a little railroad laid, not to dance around like Kansas City faggots!
 
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