Thread: GIS Yawl

Yes, this was a WCTSS event. I don't have a camera, but Simon may have taken some pix, and I believe some others took pix of us as we milled around off the event site. Maybe he'll chime in.

I'm baaak! Have not logged on here in months. Meeting Rob and sailng with another Goat inspired me to peek in and see what's up. Lo and behold I stumble on this post by Rob. It was a pleasure sailing with you and welcome to the forums Rob.

Sailing with another Goat is the best sailing fun I've had in a long time. Other than just the pure fun of it it's awesome to be able to actually see the effect of changing setup or technique vs the other boat. The two boats are so close in baseline performance that it's really apparent when you tweak something. Looking forward to doing more two Goat sailing in the future. Like next weekend at Cedar Key

We have not sailed the Goat as much as I wanted and there are only a couple tweaks from the original setup. As Rob mentioned I added carbon to my boom. There are a couple of old threads around here where we debated the effect a bit of carbon would have on a wooden boom. I'm happy to report that the differance in stiffness is HUGE. My 6:1 downhaul would easily deflect the all-wood boom to an alarming degree. The improved boom stays almost totally straight with brutal downhaul. I added an approximately 2mm thick layer of carbon tow top and bottom of boom. Will write up all the gory details with pre and post carbon weights and deflections.

So glad people like the yawl version! Life is evening out here. When I deliver the other skiff sitting in my Goat, which is on a trailer in my old home shop surrounded by boxes full of tools, I'll be rigging BLEAT and getting her ready to sail. The only construction left is to drill for the oarlock sockets and attach brass half round to stem.

I decided to name the boat BLEAT.

Originally Posted by CCBB

I decided to name the boat BLEAT.

Haha, hilarious

Originally Posted by SimonLew

I'm baaak! Have not logged on here in months. Meeting Rob and sailng with another Goat inspired me to peek in and see what's up. Lo and behold I stumble on this post by Rob. It was a pleasure sailing with you and welcome to the forums Rob.

Sailing with another Goat is the best sailing fun I've had in a long time. Other than just the pure fun of it it's awesome to be able to actually see the effect of changing setup or technique vs the other boat. The two boats are so close in baseline performance that it's really apparent when you tweak something. Looking forward to doing more two Goat sailing in the future. Like next weekend at Cedar Key

We have not sailed the Goat as much as I wanted and there are only a couple tweaks from the original setup. As Rob mentioned I added carbon to my boom. There are a couple of old threads around here where we debated the effect a bit of carbon would have on a wooden boom. I'm happy to report that the differance in stiffness is HUGE. My 6:1 downhaul would easily deflect the all-wood boom to an alarming degree. The improved boom stays almost totally straight with brutal downhaul. I added an approximately 2mm thick layer of carbon tow top and bottom of boom. Will write up all the gory details with pre and post carbon weights and deflections.

Great news from both you Simon and from Rob.

Interesting to see the performance is really similar for the two boats. It SHOULD be because the plans are so detailed (pedantic ). But that was part of the point too ... to pin down all the bits that give performance accurately so every boat would have "the good bits".

Nice to see it has worked!

On the carbon ... when Bruce played with it before it was only a couple of layers. But adding 2mm is a considerable number of layers .. how many layers would you estimate?

Thanks both for posting!

MIK

Hi MIK,

I'm not a racer at all. I think it's because I've never had a chance to do any one design racing. Handicap racing does not appeal to me at all. It would be great fun to do a (laid back) two boat development effort, swapping boats to compensate for sailor's skill and technique. Could spend many fun afternoons chasing another Goat around .

I've carefully documented the carbon boom reinforcement and will write it up but first I'm going off sailing for a few days. Here's a preview.

Carbon finished goods like cloth or uni tape are expensive but carbon tow (fiber bundled on spools) is cheap at $5 - $15 per pound, so I've been using tow on as many experimental projects as possible. The key to it is to figure out a way to control and orient the fibers in some civilized way while wetting out with epoxy. I think I have come up with a simple and effective way of doing this. Since it's tow I can't tell you how many layers but the carbon/epoxy layer is just under 2mm thick the full length of the boom, top and bottom. The forward 1.5 meter or so of the boom has an additional 1.5-2mm layer since that's where the stress is concentrated.

I don't have the numbers handy but the added weight of the carbon was about 15% of the total boom weight. And since it's tow it literally cost less than $5 plus epoxy. Stay tuned for a (pedantic ) dissertation on this.

Hey Simon, I'm definitely interested in the specifics of your carbonized boom. I was just reading about seamless carbon sleeves, vacuum bagging etc. Your empirical flex data and minimum weight gain look very promising.

I clicked on the West Coast Trailer Sailor Squadron's site earlier and found that Simon is now an award winner for his lovely GIS. His carbon fortified boom is visible, but not in action.

What pretty boats at the gathering out West. Simon, your boom looks great. I may just copy you! First I have to finish my skiff...

Now look what you've done, Simon. We've all got Boom Envy!

I looked around in my barn today and came up with a 4/1 downhaul off an old Mistral windsurfing rig and a couple tiny cheek blocks that will do for an adjustable outhaul.

Now I just have to design my new main boom. I'm thinking of a simple box structure with Doug Fir top and bottom chords and 4mm Occume ply sides, fairly deep in section at the middle and tapered toward the ends.

Time to re-read those other Goat threads!

Simon and I did some sailing together in our Goats on 2 successive weekends, once at Crystal River and then again at Cedar Key. In the week between I added a primitive hiking strap, reconfigured my main sheet, and slacked my outhaul on advice from Meade Gougeon, who was sailing by in his hot little canoe, Woodwind.

The boats seemed pretty well matched, except for that boom and the 6/1 downhaul. That and the fact that I have about 20 years and 40 lbs on Simon... We weren't racing, of course, cuz we would never stoop to that, but it was fun just the same.

Originally Posted by CCBB

What pretty boats at the gathering out West...

That would be the "West Coast" of Florida by the way

I have more Yawl related questions, so I naturally return to THE Yawl thread. I'm laying the foundation for the mizzen mast and boomkin. I've applied the newest measurement of snugging the mast closer to the tiller, 6" off the centerline. What I couldn't figure out is how to push the mast step any closer to the transom, since the transom's framing already sucks up 19mm (3/4 in) of the space between the transom face and the centerline of the mast and half of the mast sucks up another 3/4 in. Clint, unless you object I'm using the original base distance of 2 1/4"

More important for me: I'm thinking of having a longer boomkin that extends further into the hull. I'd like to secure the boomkin to the deck at two points and leave the hole in the transom out of the structural picture altogether. I dug up a picture of John's build to help describe what I mean:

mizzen1 by Texas GIS, on Flickr

My idea is to have a boomkin that reaches about as far John's strut is (but outboard of the mast), about half the length of the tank top. It will be lashed to a step there and will rest in--and be lashed to--a cradle a couple of inches alongside the mast. I would try to mimic the upswept angle of the boomkin, although it could never match it exactly and still end in the same spot relative to the sail's clew (6" up from the tank top).

This only matters now because I will be laying the partner reinforcement soon and the size and shape of it will accommodate my boomkin scheme.

Thoughts? John, any more insight into the forces that caused your original boomkin step to break? Is the new one holding up well?

Dave

I used Clint’s new closer tighter dimensions, 6" off center and I found that I would be cutting into the transom frame 19mm. That didn’t seem right so I move all the measurements forward 19mm and added a third layer of 20 mm Sitka on the original step instructions. Okay before anyone makes any comments on the really fine 5200 slop job I did sealing my mizzen box please just let me continue to greave over waiting to long to smooth out my seal job. Thank goodness that mess is hidden. One good thing, I gave it the vacuum test and I have no leaks. My mizzen box drains out through the transom. I also wondered about John’s boomkin (breadbox as he calls it) attaching point splitting and asked Clint what he was going to do. He has another arrangement that he told me he would share with everyone once he gets it finalized. I made my boomkin a bird’s mouth hollow stick with an internal block for the mizzen sheet and I’m now wondering if that may be an issue too. We’ll see.

Rod

Thanks Rod. As you noted, the 5200 mess will be hidden. That stuff is crazy to work with. I sealed my inspection ports with it and did a LOT of cursing.

I've been considering a limber hole through the transom but have been too skeerd. If you did, I'll do it.

Have you reinforced the ends of the hollow boomkin with a wrap of fiberglass? That might be wise.

When I saw Clint's boat at Mystic last summer, his set up looked like this:



He may have added to it since then...

On the boom design question. I think I am understanding Mik correctly that for a rectangular boom
(1) the core doesn't matter much
(2) the distance height and width are most important
(3) larger using lighter wood is better than smaller using heavier wood

So what about Simon's design?
light core
carbon tow on top and bottom bonded with epoxy

For greatest stiffness, the material, carbon or other on the outermost layer would be best if it cannot stretch or elongate correct? Is that not the determining factor combined with the distance apart of the opposing surfaces?