Laminating frames for small boat...What wood?

I'm laminating frames for a guideboat (like a canoe but a bit bigger). The plans call for spruce laminated frames, however here in Southern Cal, this not being the wooden boat capital of the world, there is simply NO spruce that is clear. Redwood is available in clear heart but seems too soft. There is white oak but I'm concerned about weight. I've tried doug Fir but the grain seems pretty course and it doesn't finish too well. The finished size on these frames is only 5/16 x 3/4. I'm just not having fun with doug fir. Has anyone had succes with this wood as a small frame laminating material?

Thanks
Stumped again

 

You should be able to find Spanish cedar in your area, which is pretty light (24 - 25 pounds per cubic foot) and harder then typically cedars. Douglas fur is difficult, if imposable to finish bright with any level of smoothness. At 37 pounds, it is much heavier then the framing stock asked for in the plans, but it is also quite strong for its weight. White ash is also heavy, but very strong (40 - 41 pounds), wears and bends well, plus next to spruce it is the strongest for its weight. Southern yellow pine (pretty heavy at 43 - 45 pounds) is tough and rot resistant, making a fine framing stock. It needs special care with glues, but many oily or resin filled woods do. Mahogany (about 40 different varieties) African, Honduras and Philippine are the more common available at the lumber yard, will also make a good frame.

Selecting a substitute framing stock can be difficult. Try the US Forestry Service web site to get specific details on the different properties of the species available in your area. Match up whatever you can get with the qualities you need in your substitution lumber. Try to get as close a match as you can, weight, rot resistance, strength, ability to bend, glue acceptance, etc. Key in on light, bendable and glue tolerant stuff during your search. Stiffer, heavier lumber can be reduced in dimention a bit to save weight and/or frame spacing can be altered to also suit heavier stock.

 

Par
Thanks for the data. I'll look for Spanish Cedar. I had been loking for western red cedar but was told by several lumber yards that it doesn't come clear. Mahogany seems like a good choice. I had thought of using it but didn't know how easily it would bend. My laminating strips are 1/8 thick x 1 3/4 wide which should make 4 frames after ripping. This weight issue brings up another question I've been qurious about. If by boat winds up weighing 15pounds heavier because of heavier wood used. Is that a big deal in a boat that should weigh 75 lbs? Is it not the same as if I had 15 more pounds of gear in the boat? This is probably a very dumb question. Thanks again

 

If you don't know the answer, it's never a dumb question. If you took your 60 pound boat out, the day after pigging out on Thanksgiving, which happened to cause you 15 pounds of additional girth, would you be quite as concerned. Yes, your boat will notice the difference, if measured by an accurate speedo. From a technical stand point, the boat will be slightly harmed (performance wise) by the extra frame weight, but not enough to get real upset over, unless you're going to race competitively against boats 15 pounds lighter then yours.

The different frame material species (mahogany, etc.) can have it's additional weight offset by increasing frame spacing and decreasing frame dimensions. Unless you have considerable experience building different, lightly framed craft, then you should seek help in the dimensional changes you my need.

 

If you have to portage the thing much, the extra 15# will be quite noticable. Otherwise it won't make much difference. As far as 'clear' spruce, maybe you can get get bigger pieces and cut around the knots to get clear pieces. Also try homebuilt airplane supply store or clubs. Here's a place in Corona, CA. Maybe it's close, those places and other woodstores also ship. Sam
http://www.aircraftspruce.com/catalog/wppages/sprucesparstock.php

 

weight is always important. In calm conditions real light weight can be a real benefit, but in heavy weather a heavier boat is steadier and carries through the waves better. Our bigger 2 man rowing boat weighs 260 pounds and on a rough day we push ahead of other lighter boats that are getting blown all over the race course

 

nordvindcrew,
Thanks for the post. I see what you are saying about the weight. I am trying to build an adarondack Guide boat from a book. I am to the point of laminating frames and have had 2 or three runs at it and all have wound up in the trash so far. I have tried doug fir, mahogany, and redwood. My clamping technique is I think the biggest problem. I have 6 strips 1 3/4 wide and 1/8 thick. After wetting them with thickened epoxy (after steaming) as I clamp them to the form they want to slide and move too much so that I wind up with voids and out of squareness. The book says go to the lumber yard and get some relatively clear spruce. There is none of that where I live. I'm going to try white oak and have another go at it. Has anyone else had a problem with this?

 

Try making a laminating jig on a sheet of plywoood with many clamping points. also it's a lot easier to clamp a smaller lamination of less pieces. It may be that going slow will be quicker in the long run. Wooden boat magazine has done several articles in the last couple of years showing different clamping techniques. A guide boat is a real fast slippery boat. paul neil, a tri- athelete, rows one and is very hard to beat in any race. He had a traditionally built boat but now has gone to a strip built version, but it still has the ribs added in after the hull is built and sheathed with glass cloth set in epoxy.

 

another thought. All the boats my brother and I have built use lumber yard material. We have laminated stems and other parts from the mahogany that is sold here on the East coast for building decks. It seems to work fine although our boats are built to only live about 8-10 years before we row them to death. Most of our adhesive has been PL2000 urethane ribs cut from framing stock and planking is luan plywood well soaked in wood hardner before being painted. the plywood has failed before the glue. In your case, I guess that I'd stick with the epoxy. good luck !

 

another thought. All the boats my brother and I have built use lumber yard material. We have laminated stems and other parts from the mahogany that is sold here on the East coast for building decks. It seems to work fine although our boats are built to only live about 8-10 years before we row them to death. Most of our adhesive has been PL2000 urethane ribs cut from framing stock and planking is luan plywood well soaked in wood hardner before being painted. the plywood has failed before the glue. In your case, I guess that I'd stick with the epoxy. good luck !

 

I'm only just reading posts to learn about the boats myself, but having over 20yrs of woodworking experience I know a bit about laminating. You do need to build a good jig with some plywood, or better yet MDF. It's a simple jig. I assume that the ribs are similar to crescent moons. Sounds like your ribs are going to be 3/4 thick when done and 1 3/4 wide. Glue two pieces MDF together so they are now 1.5 thick. Cut your outer profile with bandsaw in the MDF. Take the inside scrap piece and scratch awl it back 3/4 inch then cut that with the bandsaw. Now the two pieces will be a perfect sandwich for your ribs. Use Johnsons past wax or something to that effect with no silicone in it and wax the jig really good so no glues stick to it. insert all your strips and clamp like the dickens. Your strips should be cut a bit extra long to allow for trimming to fit and about 1/8 extra wide. You use clamps up top too to hold them in line as best you can. You scrape off excess when done. You then will trim off that 1/8" excess using tablesaw, planer or drum sander. Drum sander is what I prefer to use. I assume you have a drum sander to sand your strips after re-sawing them on the bandsaw so they seam together perfectly. I haven't built a boat yet, but that's how I make a round laminated arch.

 

Workinforwood, great way to do it if all the pieces are the exact same. A doubled piece of MDO board is a good base and movable clamping points that can be screwed to the base and moved around to the various lofted rib shapes do the job. use a lot of clamps and clamping points.

 

Northshore, why the ham sandwich are you steaming slats that are only 1/8" thick? They should be able to take any reasonable curve you ask for dry and cold. Try wetting them down with hot water, clamping up your lamination in the jig for three or four days, then disassembling, coating with glue, and clamping it all back up. Ya folla? Establish the curve first, then make it all stick together.

 

Any time you bend a piece of wood, you have to account for spring back. On recently felled lumber (the best kind for steam bending) the radius should be 10% tighter to allow for spring back. Fully seasoned needs a little more, maybe 15 - 20%, boiling water soaked even more, kiln dried is a crap shoot, expect a lot of breakage if the radius is very tight (like at the turn of the bilge) on this stuff.

There are many bending jig methods. I usually employ a table, some blocks screwed down over the pattern and lots of clamps. One trick is to use a steel band around the outside of the stock being bent. It is bent with the lumber and can eliminate rips and tear out in the grain as it stretches into position.

Grain orientation is most critical when bending. Run out, checks, pith and defects will surely show up as soon as you start bending. The wood will bend the easiest on the flat grain side, but will also lift the grain like the dickens, without a metal band to hold it in place until it dries. It's not particularly hard, but do expect some broken pieces during the process until you know what to look for in bending stock.

The biggest novice problems I've seen are: under or over cooking the lumber in the steam box, not watching the grain run out, insufficient arrangement for a bending jig, poor bending stock selection and using kiln dried stock.

If using kiln dried stock, try soaking them in water over night, which will make them pliable, then steam them the next day.

To prevent the laminating stock pieces from moving around when wet with epoxy, make a pocket at one end of the bending jig. This will accept the loosely stacked pieces and keep them reasonably in place. Once the bend starts, the pocket will serve as an extra hand and after the clamps are started it isn't necessary any more. Use a block and hammer to align the stack if it's a vertical lamination (the way I do it most often) and wedges against the jig on horizontal laminations. Both of these will align the sides of you pieces.

Voids can have goo packed into them after you got the clamps on. Concentrate on the clamps first, your time is limited, work as fast as you can, because in a just a few minutes the stock has cooled enough to not want to bend. Preparation is the key to successful bending, so have everything at the ready before the stock comes to the jig.

 

Are you using thickened epoxy? Instead of laminating a single piece for four frames, you could laminate each frame individually. Voids or gaps might be easier to detected and corrected before your epoxy kicks.

I built frames out of douglas fir. I had trouble with breakage in the beginning. Lots of steam, a contoured(shaped) bending fixture and bending two laminations together(at the same time) reduced my breakage woes to next to nothing.

My frames were sided at 3/4" and I bent and laminated at that thickness.