: Yes, frequently, but it can be close. And, of course, you can overbuild (or
: underbuild) either way and introduce bias. The old wood canoes used to
: weigh in at about 65 to 75 pounds dry. They had a heavy canvas and oil
: paint covering, and thicker wood sides, as well as thicker and wider ribs.
: And they were seldom dry. I'd guess they soaked in another 5 pounds in
: water after a few weeks of use.

: Not necessarily. Which is going to be stronger, a blanket or an I beam? The
: physical size and shape of the rib acts like an I-beam in how it stiffens
: and strengthens. The thicker the rib, the more the effect. A layer of
: glass cloth is far more flexible. The surface bonding effect you obtain
: will keep the strips from falling apart, but it does little to stiffen or
: strengthen the hull itself.

: Exceptions do occur. Polyester resin would be stiffer than epoxy. Laying the
: glass in the shape of a rib would also make it stronger. Consider using a
: 1/2 inch diameter piece of foam as a rib mold, spot gluing that to the
: inside of the boat, and then laying glass over it. You'd end up with a
: very stiff tunnel of fiberglass about 1/2 inch high serving as a rib. This
: would be much stronger than a flat layer of glass cloth, at least in
: certain directions. I've seen designs which in fact specify ribs be made
: in such a manner, with a foam, or paper core.

: As for speed of application, or time involved. Not much time is needed with
: the ribs. Steaming them all at once you would take out onestrip of wood at
: a time and bend it around a mold. Working with 3 or 4 such molds at a
: time, you'd be pulling a cool rib out about as fast as you could get the
: wood out of the steam box.

: Now, making all the molds for those ribs would take some time. With a
: symmetrical hull--or one that was fairly close to being symmetrical, you
: might use the same mold for 2 to 6 ribs. with 4 ribs to a foot, on a 16
: foot boat, figure on 30 to 35 molds.

: Bending each individual rib is fast if you have the space to work in, so
: figure an hour for bending all the ribs, and setting them in their slots
: on the mold. After that, you just nail on the strips.

: With glass you need to add in a skim or seal coat, wetout coat and one fill
: coat. Inside a boat you don't need to completely fill the weave, but you
: do need two coats to be sure that cloth is well covered. You might skip
: the seal coat but that uses more resin. That's about 3 to 4 hours, plus
: any sanding time to remove lumpy drips or blobs, plus time spent waiting
: for the resin to get hard enough to sand. With the wait time, this could
: go three days or, typically, a home builder would do it over a couple of
: weekends.

: Fasteners? What are you using? Would dowels work? Drill out the wood, replace
: the sawdust with a round piece of wood of nearly the same weight.

: Seriously, tho, I do understand that issue. When you try to use a bolt or
: woodscrew with a thin wood hull, whether it is strips or plywood, the
: surface of the wood is not going to take a lot of force over the small
: area most fasteners cover. So you need to beef up the area around your
: fastener with more wood, additional layers of glass, or use wide and
: heavier fasteners which spread the loads over a bigger area. For example,
: embedding a "T" nut for mounting rails for adjustable foot rests
: adds much more weight than the "T" nut itself.

: Boats with ribs on the inside were a good idea for many years, but you can't
: just pop them out of molds, so you won't see them made in factories. And
: building one at home means lots more setup time and more jigs. For a
: single boat it is not practical. It is barely practical unless you want to
: start a small factory. Just guessing here I'd say you probably wouldn't
: break even with time and money versus glass on wood unless you made
: probably 6 to 10 boats off of a mold. After that I think you'd save some
: shop time and about $25 on the glass and resin. I may have better numbers
: on this in a year or so. I am strongly considering building a mold for a
: 17 to 18 foot touring canoe and using it in classes. Hopefully I'll be
: able to offer a class where someone can build their own canoe over such a
: form in 4 to 5 days. That would be three to 4 days working at assembly on
: the mold, varnish in the evening, come back the next morning to put on
: gunwales, decks, and hang seats and thwarts before another coat of
: varnish. The next morning varnish the inside, and take the boat home in
: the afternoon. A classic wood canoe with no glass. Or, spend a couple more
: days and glass the outside. You'd have a boat in a week. Rgiht now that's
: the goal, but the plans are still being worked on. Talk to me in 6 months
: or a year.

: PGJ

Hi Paul,
The number of molds needed for a thin planked, bent-rib boat is suprisingly low. Most boats I've seen being built or worked on myself had the majority of the ribs put in after the hull is righted off the molds. There are either pre-bent ribs or temporary frames in the hull for righting. Most of these boats were clinker, the others were caravel.

As for weight between glassing and fasteners, I'd go with fasteners. Some of the boat nails (square copper) were as thin as a heavy needle and absolutely needed a pilot hole, on thin wood a good brad-awl works to pilot. An awful lot of these 1" boat nails in a pound.
Clenching over the ends inside makes a 'smoother' inside compared to roved rivets.

On polyester resin, I wouldn't put it on any wooden boat as sheathing, the resin is too brittle compared to epoxy, and is not as adhesive. I wouldn't be inclined to put even epoxy on something like the PAL, I've noticed that older boats don't do well when sealed like that.
The use of foam or rolled paper for making glass ribs is usually only used in lighter weight pure glass/resin hulls.

Mike Savage
South West Cork