Thread: Goat Island Skiff

Paul,

I've found that to take a curve out of laminated spars you have to overbend the sticks just a tad, while the epoxy sets. This way the laminated stick springs back straight.

The big question is how much bend is a tad? My thinking, which seems to have worked OK, is if the curved part is the more rigid of the two then the tad needs to be bigger than if the curved part is the more flexible.

The absolute value of the tad is up to you

Paul,

I had the same experience and got the same advice, "No problems. It is easy." (And the like..). I didn't believe it and still don't. I struggled with assembling the mast. The ladder frame had a bit of a bend to it and I cut out the spacers and reglued them. That fixed the bend but gluing the wide staves in place was still a nightmare. I worked out a method of clamping the assembly together that worked for me.

Figure out what works for you and go with that. As Mik says, if not sure, dry fit and practice, practice, practice the assembly process.

(I've been playing hookey from work since the end of last year. )

Thanks for the tips, guys.

The curve is tiny. The center of the ladder is just a few millimeters east of where it should be. And it is smooth over the length of the mast. You'd never even see it if I didn't have a string stretched right above the frame to check.

And since the deflection is parallel to the faces of the wide staves, I'm sure it will be easy to straighten out. A few small nails should do it.

Can't wait to get this done. Once the mast is structurally complete, it's "only" a matter of a epoxy-coating the spars and varnishing the spars, tiller, and foils before I'm really sailing.

I got my mast glued up last week and found a little time this weekend to start tapering the bottom and rounding the corners. And now I need advice from the collective.

Approx how much thickness will the cloth, epoxy, and varnish add around the bottom of the mast?

The fit right now is very tight, both at the step and at the partner. So tight that I had a job getting the mast out again. I know that I can enlarge both holes, but that means destroying the epoxy and varnish on them and re-applying. I'd rather taper the mast a smidge, if I can. But will I have to taper so much that I reduce its strength too much? Are we looking at taking 2mm off each face? Less? More?

With respect to rounding the corners, I must admit here that I am a BIG CHICKEN. I have a nice plunge router and just the right bit to put a 12mm radius round edge on the mast. I even tried it out on some scrap cut off the same plank that made up the wide staves. But I just could not bring myself to use it on the mast. The thought of those spinning blades ripping chunks out of my newly-glued mast made me feel weak. So I'm rounding the edges by hand. Go ahead and call me chicken. I won't argue.

B-bwock bock bock!
(my very best attempt to spell a chicken clucking sound)

I picked up my 16-foot beauty, slapped it onto my router bench that was clamped to a fairly shaky utility table, and shoved it through. Ok, I did have two feed rollers to keep it balanced. I'm sure you can set things up to take advantage of the power tool you have waiting to serve you. Start with a 3mm shave, do all four corners, then increase the depth and repeat until it's done.

I can't say I have a good answer for the fitment question. My mast has 'glass, but no additional layers of epoxy or varnish yet. But if you still have those layers left to add, you could also re-coat the edges of the holes at the same time. I favor making the holes match the spar rather than the other way around.

I do seem to remember Christophe saying that he had to take a rasp to his mast partner. Maybe I'll have to do the same. <sigh> Yet one more reason why I should have made my sticks first.

I used a rasp to make the partner fit the mast; the step was fine. Yep, I had to re-coat with epoxy and varnish.

For rounding over the edges, I used a 6mm (1/4") round-over bit in a laminate trimmer and just did it by hand. Yeah, I seem to remember the plans calling for a 12mm (1/2") round-over but I used what I had. Maybe I left a smidgen of weight on the mast but I'm happy with the results.

Thanks, Bob. I'm becoming resigned to doing the same as everyone else on the partner. Given the choice between weakening the mast and doing a little extra work on the partner, I'll choose the latter.

With the varnish now dry on my spars and most, if not all, of the hardware sitting in a box on my desk, I thought I might take my first sail today. But with 2 inches (that's 50mm for you non-Yanks) of rain already down this morning and at least 2 more inches due by nightfall, I don't think that's happening. And tomorrow I leave town. So it will be at least Aug 27 before I can hoist a sail on my poor Goat. Aaargh!!

Anyway, to the question at hand:

I was showing her off to some guests yesterday. It was a hot, sunny day and the boat was sitting in full sunshine. Someone asked about the deck plates and so I opened one on the rear tank. Imagine my surprise when the cover blew out of my hand with an audible "whoosh" and the tank top dropped visibly. I guess that thank is airtight.

The forward tank did not "whoosh". I've never seen even a drop of water in there, neither after rowing in a chop nor after heavy rains, so I consider the tank watertight. But there must be a pinhole somewhere which allows the pressure to equalize.

Should I poke a tiny hole somewhere in the rear tank to allow the same? I'm concerned about the damage pressure changes can do. One of my kids' favorite science demonstrations is to crush a steel can by heating it, closing it up, and letting it cool to room temperature. Wouldn't want that to happen on my rear seat, nor to have a seam blow open.

Or am I worrying for nothing?

Just keep the hatch lids off when storing the boat, or keep them cracked if the boat is outside. The forward hatch is probably just leaking through the non-airtight hatch, that's all.

I've also found on hot days the hatches can deform and be very difficult to open. A splash of cold ocean water helps immediately, keeping them lubricated with some sort of substance helps too. I use vaseline, but be sure your hatches and rubber seals can take vaseline, some can't take the petroleum products, it usually says on the hatch or the packaging.

Some lube and keeping a cracked hatch will keep water out and you won't get that air pressure differential if you're worried about it.

The forces from just a bit of air pressure are amazingly high. I try to leave the deck plates cracked until I go sailing but I forget to do that half the time and then they open with a big woosh. Have not heard of any Goats blowing up so the structure must be up to it.

Your question piqued my curiosity so I did a bit of basic ideal gas law math to roughly see what the pressure difference is (remember P1T1=P2T2).

Lets say you close your tank up in the morning before setting off when the air temp is 80F (27C) then mid day the boat sits in the sun and the air in the tank heats up to 110F (43C). When you convert all that to Kelvin and atmospheres and back to silly American units we get a pressure rise of 0.78 psi. Not that much pressure but look what happens when you distribute that pressure over the area of the aft seat.

The aft seat has a surface area of roughly 1333 square inches so 1333in^2 x 0.78psi = 1045 pounds. That is the total force trying to rip the seat top off the boat . Maybe a tiny vent hole is not a bad idea.

Tanks, guys! (Sorry. Couldn't resist the pun.)

I think I might just drill a teeny hole somewhere. I'll get a few drops inside when I capsize, but that isn't a problem. Thanks again.

I'm thinking on centerline is least likely to get submerged in a capsize.

My Goat has sailed. Really sailed -- no oars this time. My daughter and I took it out for just an hour or so, embarrassed ourselves, scraped it up, made some mistakes, had a ball. No pics -- unless someone at the neighbor's lawn party snapped some. But it really finally happened.

I just finished attaching the last of the hardware this morning. (I had run into delays getting the rudder hardware to fit and figuring a downhaul configuration which worked.) Within minutes, the sky darkened and the first of several squall lines hit. I was pretty sure I was not going sailing today.

But the weather maps showed a two-hour gap between fronts, big enough to have some fun in if we were ready to jump on it. My daughter was game, so we went for it. We pushed out into too much shifting wind and a messy chop with epoxy still curing, no reefs in the sail, no hiking straps, no non-skid on the deck, and no prior experience with a lug rig. Woo-hoo!

Okay, "pushed out" doesn't quite cover it. The launching area is surrounded by "clotheslines" holding the neighbors' dinghies out beyond the surf. With an onshore breeze, we got hung up on those and floundered for a bit. The lawn party clapped and cheered when we finally cleared the lines. Then we clipped someone's outboard and took a bit out of the port gunwale. But we did finally make it.

We thrashed around a bit, getting the hang of the rig. Made some mistakes. Learned a lot. Didn't hit anything else. Had a terrifyingly fast trip back to the beach, dead downwind with the swell driving us along, aiming for the one small stretch of rock-free beach next to the ramp. Dang! That boat is fast downwind! Had it all back inside before the next storm hit.

Lessons learned: Finding the right downhaul configuration is pointless if to forget to pull on the string. Putting varnish on the spars was fairly pointless since so much scraped off on the first sail. The base of the mast needs some grease or it takes forever to pull loose. Non-skid is essential. The oars need to be tied down when not in use. Your GPS can't tell you how fast you are going if you don't turn it on.

All in all, a fantastic, if short, sail.