| Subject:
Andrew Haill reports in from Thunder Bay: still sailing, hoist bridle suggestions -----
Original Message -----
From:
Andrew Haill
To: Al Schonborn
Sent: Friday, October 26, 2007 1:26 AM
Subject: bridle
Al
Hope you are doing well
perhaps you would forward this
to the new Wayfarer owner in Indiana that you had correspondence
regarding her inquiry about hoisting a W. There was no
address to directly reply.
thanks
Andrew
PS Still sailing here..
(late Oct sunsets at 7:00pm being one benefit of the west
side of the time zone) although it is starting to get a bit
chilly. Almost all the big boats are out of the water...its just
a lonely W on the lake. Some pictures of the last few evenings
out and the moon over the Sleeping Giant as we were returning...
enjoy.
   ... and regarding hoist bridles: Hi Bridget: First, a welcome to Wayfarer sailing… you have chosen a great dinghy. Although where I sail (in Thunder Bay at the top of Lake Superior) is some distance from Indiana (and the game is hockey and not basketball), of particular relevance is that we both launch from a hoist. There are big benefits to this, particularly that trailer bearings stay out of the water and you can launch / retrieve without your car. As you noted however, one needs a hoist rig. Here is what we do. I would guess that your 4000 numbered Wayfarer is a MkI… I have a MkIII which is slightly different, but the other W here is a MkI. This MkI has a shroud attachment fitting having multiple holes in it to allow adjustment of shroud length and mast rake and it was an easy matter to fit a shackle in an unused set of holes as a hoisting point. The hull attachment plates (chain plates) are perpendicular to the centreline of the boat, and so the bridle angle during hoisting (which is more inwards than the normal angle of shroud pull) just rotates the shroud attachment about the pin connecting that fitting to the hull attachment plate. Nice and simple and hopefully you have this arrangement. My MkIII has shroud turnbuckles without any convenient shackle mounting locations and the hull attachment chain plates are oriented in line with the centre of the boat which is not ideal in that the inward bridle pull slightly bends the plates in. Having some shroud tension lessens the effect but I'm still searching for a better solution. A shackle might replace the existing shroud to chain plate connection pin but it would still pull inwards and small shackles unfortunately don't seem to have pin diameters that are a good match. A separate installed hoisting point as Dick suggested would work but it is nicer if one can utilize the existing shroud fittings. I am now experimenting with a 4-point bridle to reduce bending of the hull attachment plates… the fourth line goes down to connect to the vang anchor point at the base of the mast. Of course any 4-point support often practically becomes a two or three-point support (like a chair with a short leg) and I have adjusted the relative bridle rope lengths so that the initial portion of the load is on the vang attachment before the two side ones are tensioned and also hold the boat level. The bridle now attempts to pull the mast up out of the boat which of course it can't do because of the shrouds … thus the lift on the hull is still via the shroud attachment points… but now partially via the mast and shrouds in a more appropriate pull direction. I'm convinced sailing loads are far higher than any occuring when lifting the boat this way. The bridle is simply made of good quality rope with a substancial load rating and not cheap hardware store stuff (I've used a extremely strong 5/16" but 3/8" might generally be better). The hoist hook end is a suitably sized metal thimble eye to protect the rope loop from hook contact or abrasion. Some boats use a large metal ring instead. The boat end of the side bridle lines are steel S-hooks which for the MkIII turnbuckles are bent to fit into the gap beneath the U-shaped shroud end fitting that is pinned to the hull attachment chain plate, or in case of the MkI just hooked into the shackles installed for the purpose. For the aft bridle attachment I use a snap hook into a dedicated strap eyelet bolted through the rear bulkhead and a glued-in backing plate. The MkI uses the hiking strap connection. It is true the hiking strap attachment point should be pretty strong, but hiking strap forces are horizontal and mostly load the fasteners in sideways shear. Compare this to hoist loads which are more upwards and now attempting to pull the fasteners out…screws into thinnish fibreglass are not as strong in tension as when pulled sideways. Also ensure the pull direction does not go across any eyelet fitting which prys it out, but along it (this was one problem in using the hiking strap attachment on the MkIII). Check carefully that the screws (bolts ideally) and the backing material are strong and adequate… if there is any concern, install at the base of the rear bulkhead a dedicated attachment point that is through bolted with a backing plate. A separate bridle line (left slightly loose) could always be hooked onto the traveller as backup to catch the boat should those hiking strap screws ever let go. I personally wouldn't go to the trouble of a wire bridle… decent rope can be strong enough and is far easier to make and adjust. The majority of the dinghy fleet here are the far heavier Lightning class boat and they also use rope bridles and a similar system. A rope bridle is also easy to crumple up and throw into the back hatch. However if you are set on using wire I might suggest leaving the aft attachment as rope since it has less load and is the one you need tweak to get the boat hanging level. The biggest thing you can do to lessen the overall forces in your bridle system is have the whole thing as long as possible… the more vertical the bridle ropes are when going to the hook - the more effective it is and the less load carried by each rope compared to a flatter bridle. For example to provide 100 lb upward lift force, a bridle rope at a flatish 20degree angle to the horizontal actually experiences a load of almost 300 lbs in the rope... at 30deg 200lb, 45deg 140lb, and 55deg 120lb. The achievable bridle geometry will of course depend on your hoist set-up and clearances, but from a force perspective- the steeper the better. The other advantage is that the chain plates are not pulled inwards as much. It's always a bit weird seeing one's boat hoisted overhead but it is a great way to get a Wayfarer in and out of the water. If I may offer any advice it would be to always first moderately load the bridle and re-check connections are properly hooked in and aligned before proceeding to fully lift the boat.... if there is any accumulated water slowly lift just enough to let it drain out, and of course the golden rule of safe hoisting is to make sure neither you nor anybody else is ever under the load. Good luck with it. Andrew Haill W9657 |
UK-Halsey Sailmakers’ latest rules quiz (23)
deals with some aggressive sailing in the J/109 fleet this fall. Two
boats were VMG reaching with spinnakers. The windward boat pushed the
boom from the starboard side of the boat to the port side and then
hailed starboard. Was he on starboard? Watch the animation, read the
quiz, read the facts found and then read the rules that applied. Follow
the hot links to get the exact wording of the rules. Feel free to
replay the animation as many times as you want. It’s animated, it’s
free, and it’s private (no embarrassment in front of crew, competitors
or judges). And best of all it is the easiest way to learn the rules of
sailing. Take your time and study the more than 20 other quizzes on the
site.