assembling a better build guide?

[Chad]

SInce there's now bunch of folks that have built boats, and the original guide was written pretty much in the dark, whaddabout we put together a what worked/what didn't work/what we'd have done different thread? Realizing that there isn't a single "best practice" method for building the overall boat, I think there are several pitfalls that can be identified and avoided.

To start, some of the things I think are really important are:
Cutting the hull panels (for folks that don't order kits). I think it's pretty important to use a long continuous batten to fair the curves, and if you do it makes even more sense to use that batten as a pattern for a router with a flush-cutting bit. I also think it's pretty important to use a hull panel butt-splice method that doesn't create hard spots in the hull panels. It doesn't matter if the full-length panel is at the front or back, since at least one of the splices will occur where there is lots of twisting and natural curvature from chine to shear. Sloping scarf cuts are best and not at all difficult with thin ply, 2nd choice would be a simple glass joint, and 3rd choice would be using a butt block or doubler but making sure the panel was pre-curved to the natural chine to shear curvature (so place shims at each end of the joint, put the doubler in place, and then weight down the middle so hull panel and doubler cure in a bent shape).

Curving the frames. Every build has needed to do something to fix the unfairness caused by the straight sided frames. One recent post to the old forum just mentioned "it's a pity I've already cut the frames [straight]...". 17 months ago I wrote: I propped my side panels into place, adjusted the shear to the plan widths, and then took scribed templates of the curvature at each frame location. My templates had arc depths of 11/16" @ F18, 5/8" @ F53, 11/16" @ F89, 7/8" @ F110, 3/4" @ F124, and 7/16" @ F169.

Cockpit design. Almost nobody wants the narrow forward cockpit shown in the plans, and needs to cut a bunch of material out of frame 124 and scab stuff onto 110 to hide the holes this creates. So if cutting from plans or patterns, folks should think about this ahead of time, and if buying kits it may be better to ask for these frames to be supplied without any cutouts.

Stringers. The consensus among all builders is that the hull panels aren't stiff enough between frames, especially in the back of the boat where the panels are pretty flat and the frames are spaced far apart. I'm convinced that full-height longitudinal stringers that tie the cockpit sole to the hull bottom are the best solution to the aft two bays. For the hull side panels, it's hard to beat the fair curve of continuous bent wood stringers to keep the thin plywood from doing odd things. 19' long straight-grained sticks are hard to buy, but easy to splice together.

Build jig. I built on a jig to the published offsets, and then had to use a lot of force to push the side panels into alignment to make them meet along the chine. I wasn't comfortable with just stitching the panels together and letting the shape be what it may though- such lack of control is contrary to my nature. I suspect that the offsets are off a little (due to the assumptions made about the developable surfaces of the hull panels, most likely), so there's still some work to do in figuring out a best practice here. Both methods can produce a fair hull, but one will be closer to the design shape in the rocker, the other may be a little off.

It's geometrically more efficient to sweep the spreaders and chainplates further aft than the plans call for, and if I were doing this again I'd probably place the chainplates further outboard, behind frame 110 instead of in front of it. I laid mine out based on a 30 degree line hitting f110, so instead I'd continue the 30 degree line through f110 and place the CP on the aft side.

What else?

[jerome]

chad,

great thread.

İ wrote a long answer, got logged off and lost it all. So here is a summary of what İ added to your itens and should be adressed somewhere

-cabin top for short cabin : There is an issue with the plans and therefore the suggested construction method. Torturing ply panels might work for the original long cabin but was certainly not thought of for the short cabin. Panels cant take that twisting over such short length.

-cabin hatch : nothing in plans

-keel : there is a mistake in the plans which should be adressed. İf you build according to plans you will start with max thickness at 40% chord (that is not a Naca 0010) and end up with max thickness at 49% (i dont even know what that could be ) Fact is you will end up with a Frankestein type profile, and you will NOT have a constant profile throughout length of keel

-bulb : no one is building according to plan

-keel box: cant build with just the infos in plans.

-bow piece : plans only give 2 dimensions. You need 3 dimension to build this piece as it is shaped in wood.

-bunkers : needed or not ?

-compression post : nothing in plans. Nothing either for upper and lower supports/reinforcements

-mast base : nothing in plans


Lamination /fairing is also a major issue that should be adressed.

As far as rigging, İ completly agree that this is a serious weakness of the whole building process. Cant just assume that builders will guess. A basic configuration should be suggested.

There was more in my original mail but İ cant remember for now. Will update later.

Overall, this thread just made it clear to me that the first builders , the ones who did it with no help , are real heroes, and that if İ knew beforehand that İ would have to dig answers for so many unexplained building points İ probably would not have started this journey !

cheers for now.

[Ron Bowman]

This is a great idea, Chad. I agree that the original build guide needs more and better information. And Jerome, you hit the nail on the head with your list of things not adequately covered.

Something that keeps crossing my mind when I read build threads is that sometimes the advice that is given is more work than is justified by the problem. One of the attributes of a "best practice" should be ease of construction. If our focus as an organization is on amateur builders, we need to be mindful that there are lots of ways to skin a cat and the most difficult isn't necessarily the best. Finding ways to cut corners (without sacrificing safety), to make it easier and cheaper for people to get a boat in the water, is a good thing. There's a tendency by new builders to err on the side of using the hardest solution to protect against the unknown. It would be nice if we could cut through that confusion a little bit to assure people that there are easy options that are good enough.

Ron

[Chad]

Good point about seeking perfection for perfection's sake, and the tendency across the racing community to look down on things that aren't flashy, elegant, and the latest thing. I know I have a bit of that in me, trying to always optimize everything. I know from experience that this is a big part of winning programs, but there are plenty of examples of shit-hot sailors winning with amusingly inefficient equipment. I've never seen it myself, but I hear it happens...

My goal would be not so much dictating the best possible solution, but to show several examples of successful methods that builders have used for each step of the build, with a pros/cons list for each method, along with a list of "oh crap, that didn't work" methods. Maybe this is getting more into Kevin's how-to database, versus a single narrative document, I dunno.

[admin]

Great thread, I just found it while activating another new registration.

One thing I remember is how when I added the sheer clamp the boat seemed to become: a lot more solid and a lot more fair. It left me wondering when would be the optimal time to add it, e.g., before stitching in all the frames? Don't know if that's feasible but it certainly would help with the overall shape and fairness of the topsides/deck joint.

Another idea is whether "spotwelding" the long tape fillets with tabs of 6 oz unselvaged cloth is a better method of holding panels together so that you are not glassing over cable ties. Not sure I ever came up with the best technique, but that was a challenge...I think I still have 4-5 ties enbedded in my hull froward of F53.

[Kevin]

Jeff added the sheer clamp before the frames with good results.

I fillet/taped over zip ties and 100% agree that it's the wrong thing to do. Use 1/2" pvc tubing under the zip tie to align the panels, small fillet between each one, remove ties, fully fillet and tape seam. Frames could even be added before the full fillet and taping so that you are in assembly mode first, and then in taping mode once you have essentially established the hull shape and symmetry.

Tape with biaxial tape is another recommendation I have. More strength and better conformance to the curves of the chine and hull/frame joints.

Add the slight curve to the frame sides per Jeff and Chad's experience to get the hull panels more fair.

That's my $.02 for right now. Kevin

[admin]

I'll go even one step further with the biax tape recommendation. I strongly recommend Jamestown's WSY 727-10 four inch tape. It's 15 oz and comes in 10 foot minimum, but you can spec a longer roll. This stuff is the bomb. I made the mistake of ordering some crap from Boatbuilder.com, some 9 oz stuff that was so bad, when I got the new roll from JD, I seriously considered ripping out the old biax and redoing it with the Jamestown product.

This stuff is absolutely creamy, it practically lays itself and the edges feather out beautifully, even with my crappy technique. I sent some to a friend who was redoing his mast step on an older boat, and he loved it too. I didn't think there'd be that big a difference with biaxial tapes, but there is a huge difference with this stuff and I had any brains at all I'd order another 100 feet of it just so I'll have it when they discontinue it for some bizarre reason (not saying they will, just a born pessimist).

[Chad]

Agree on the "spotweld" approach. I used 1/4"R x 4" long fillets, covered by little 4" squares of light cloth placed diamond-wise across the joint, and it worked very well. Can't even tell where they are, now that they're covered by the biax tape.

Interesting comment about the biax tape, Tim. I stayed away from any of the West-branded tapes just because they charge 2-3 times what everybody else does. I think their carbon tapes and uni are priced even higher. So I used Jamestown's 17oz biax which is probably overkill, but I couldn't find anybody selling lighter stuff. It went on just fine. I used plain-weave 6 and 8 oz tape for all the joints above the mid-panel stringer though, and for glassing the smaller stringers and other minor joints.

[Ron Bowman]

I guess I'm the Voice of Mediocrity on the zip tie issue. What's the concern if we tape over the zip ties? Seems like the spot weld approach is a lot of extra work. If a person enjoys doing that extra work, great. But if a person is trying to get a boat in the water as efficiently as possible, taping over zip ties avoids that extra work. I think the best practice is to fillet and tape in one step right over the zip ties. Wet out the tape on a table or bench covered in a plastic sheet, paint the area to be taped with plain epoxy, apply the fillet, and then carefully place your tape over the fillet and smooth it in place. After it all cures, snip the zip ties and forget about the little bit left inside the fillet.

Ron

[Chad]

Zip tying over little pieces of PVC tubing really helps align the chine joints, so the spot weld approach is needed in that case. It takes maybe a half hour to spot weld both chines, so it's not a hardship at all. I did tape over a couple zip ties that held my frame bottoms to the hull bottom panel, no problem.

[jerome]

İ used a micro fillet approach and did not do spot weld. Basically placed a small fillet in between all zip ties and let cure. That was enough to hold panels in place but İ did not step into the boat. Then removed zip, apply slıghtly larger fillet and tape. Worked out great for me.
One thing that bothered me about fileting with the zip ties is either you have to make mega fillets and spend lots of resin and colloidal, or really zip tight your panels really close to the edges.
İ think İ zip tied something about 1 inch from edges. Try covering that up with colloidal putty and you have a huge fillet which will get hot and fume while curing...Not sure oyu even have time for placing tape while it is still fresh. (By the way İ used continuous tape whenever possible. Example : hull to side panels.)
That is at unless you are working in rather cold weather or use Extraslow hardener.

[M&S]

Gentlemen,
This is a first draft of how to for the building guide. Please read and critique. input is welcome.


HOW TO MAKE THE STEM TIMBER.
OK The original drawing in the plans lacks just a bit of detail so I’ll add a description of my method of making it.
For the example, our work piece will be one and one half inches in thickness, 27 and 5/16 inches in length and 3 1/2” in width. You should be able to find nicely sized 3/4” thickness Oak at the lumber yard or big box store. This is regarded as 1” stuff. Buy a 1x4 about 6 feet long.
In your shop cut it into two pieces 36” long or thereabouts. glue these two pieces together on their flat faces to make a 1 1/2” thick 3 1/2” wide by 36 inch long workpiece. (A note on gluing;
good practice is to wet out both mating surfaces. This may seem a bit over the top but as you progress, the sense that you do not have a dry joint or raw wood hidden somewhere to absorb water is priceless. You will gain a feel for how much glue is needed to cover the area adequately with a little bit of squeeze out. Clamping is recommended but don’t overtighten. I like to use spring clamps for many small parts like this. Clean up the squeeze out now and put the stem timber aside for the glue to cure. You want one edge to be aligned along the long joint.
Before any cuttiing is done we need to mark the layout lines to cut to.

Mark the total length at 27 5/16” (693 mm). cut to length now.

Your work piece is 27 5/16” x 1 1//2” x 3 1/2”.

Mark a centerline on the long axis on the wide face, back and ends. Label top, face, back and bottom . This does sound tedious but bear with me.
The cross section of the bottom will be a triangle (to fit between the hull side panels). The total included angle is 40 degrees. From the face and botton end centerline you have drawn mark the two angled sides. The ends of these lines are 1/2” on either side of the centerline on the back of the workpiece(1 inch) total width. this is about a twenty degree angle each side.

Now we go to the Top. On the FACE of the workpiece mark 1 inch from the centerline to both right and left Starboard and Port. These points can be connected on the face surface with the single centerline point at the bottom of the face.
This is the shape of the front face of the stem timber.

Return to the TOP of the Stem. The two lines on the face of the stem intersect with the top 1 inch to either side of hte centerline. From these two points you will draw lines to the back of the stem piece at 23 degrees.
To make it simpler, the two points are 1 5/8” on either side of the centerline on the back edge of the stem piece.
connect the these points.
Now place the stem piece face down and connect the top and bottom lines on the back to each other.
The Top of the stem is a trapezoid. 2 inches wide at the face; 3 1/4 inches wide at the back face. connect the lines.

Cutting will be discussed next.