Infusion (see CEW) vs. bagging
I’ve never built a boat–full disclosure–but simplistically there are three ways to do the resin lamination. They differ in the way the resin is applied and, more importantly, how the excess resin is eliminated. Excess resin adds weight without structure.
In the order in which excess resin can be eliminated and hence hulls increasing lightened:
- Hand lamination. The cloth is put in the mold and resin is slopped on by hand. Then the excess resin is squeezed or scraped off by hand tools.
- Vacuum bagging. The cloth is put in the mold and the resin is slopped on by hand (same as hand). Then a plastic bag is put over the whole thing and a vacuum is drawn through it. The vacuum sucks AWAY more excess resin and more evenly than the hand method can. So say the vacuum baggers.
- Resin infusion. The cloth pieces are all put in the mold at the same time, temporarily held in place by some sort of sticky stuff. No resin is slopped on. The plastic bag is put over the whole thing and a vacuum drawn. Then, the resin is sucked (“infused”) INTO the bag-flattened cloth in precisely controlled amounts. Hence, there is no excess resin. Supposedly, the resin infusion method results in the least necessary amount of resin in the final laminate, and hence the lowest possible weight for any given structural strength.
Each of these methods results in increasingly expensive manufacturing cost for the same hull.
Experienced hand laminators or vacuum baggers may argue that the more complex and expensive processes are not worth the cost because the weight saving per unit of strength are either non-existent or overstated. That could be true if they are very experienced in their craft, or it could just be their form of marketing self-interest.
TMK, only Placid, Swift and Colden use the infusion process for canoes. Hemlock and a lot of old time small builders are hand lamination. Don’t know what Wenonah, Bell, Vermont and Mad River do.