Plywood Boatbuilding for Virgin Builders - Part 3

by Dick Koepp



First, assuming that you have all the skeletal frame members installed and faired smooth and true to the lines of the planking which will attach to it, now you must come to a real test, installing the planking. For purposes of this article, I am ONLY addressing plywood planking here.
Tip here, paint as much of the interior surfaces of the inside of the boat as is possible now, it is easy to reach the undersides of the frames, etc, and will be tough to do once the boat is turned.

Now, the key here to successful planking is to lay out your planks carefully before doing any cutting or gluing. "Dry fitting" is a must here. Start with the stern (transom) planks first. There are several reasons for this: first, the surfaces are usually almost flat, thus making it all so much easier, second, no bending usually, and third, easier to fasten. Since most boats use standard 8' plywood sheets, you will have to connect two panels together as you move forward in the boat bottom. The two sides of the planks will meet over the keel and will be fastened onto and into the battens and frame members (based on the plans). Leave plenty of overlap, dry fit and mark each panel, NOW you must decide where to do butt joints covered extensively in Glen Witt's must-have book: Boat Building with Plywood. Butt joints must fall between frames, so you have to dry fasten or measure correctly. Be sure that you lay in the forward panels also before you fasten, because you might have moved a panel for what ever reason, and don't want to come up short at the bow (which actually happened to me!). The forward panels most likely will need to be bent or "steamed" into position. (See previous article on Steaming with hot water and rags, Web Letter 9). These are gonna be the toughest panels to install, so you need to really be careful. Take your time and use gaskets, temporary screws and/or clamps to hold things down while you measure and carefully cut off the excess from the panel. Sides: once you have installed the bottom panels completely, allow them to dry for 24 hours, then set about trimming the side edges of the chine smooth and fair, using a scrap piece of plywood to let you know how it flows. Once this is done, install the sides, again, be aware of any butt blocks and allow for them between frame members.
TIPS: Once all panels are rough cut and dry fitted, you need to mix up a big batch of glue, go overboard, running out will spoil everything! Get someone to help you. It is so much easier and quicker with a helper. I do not use ring nails anymore, not with the advent of the new generation of power screw drivers. I pre-drill, countersink and start every screw in every hole in each panel ahead of time. True, one could just snap lines and drive screws without a pilot, but you will NEVER get them all to go below the surface, and the resulting effort to sand them down is God awful! Use clamps and gaskets as needed (see previous article). Once the glue is on, and the panel positioned, drive the screws as quickly as possible. When all is installed and dried, fair the hull and make it smooth over its entirety.

Time to Fiberglass:

As stated elsewhere, the whole subject of fiberglassing is covered better in other books. Here I just want to point out some things I have learned to try and make the hull turn out "clean looking" and smooth. First, be sure you get rid of ALL holes, gaps, gouges, etc. Use a hard setting wood putty and build it up in layers if necessary. But be careful, if you have ended up with a significant gap, say somewhere at the keel, you really need to ask a pro for advice. Putty will not correct a fatal flaw. It is used for cosmetics only, remember that!! Now is the time to add any other wooden members to the hull, such as a keel log, lift strakes, or splash logs (follow your plans as to how to apply each of these). Ok, so everything is fair, puttied, and sanded, now apply your fiberglass cloth per the users instructions.
Tips: Always use gloves, always buy extras of everything you need. You will use them I promise. I keep a ton of old coffee cans stored up for the time when I will start fiberglassing. Also stirring sticks, a whole load of extra catalyst. And the most important tip of all, NEVER EVER try and fiberglass below 60 degrees!! Even if you have to heat the building site, you must have heat to set up the resin. Based on the system you use, polyester or epoxy, you will need to prepare the surface for the finish paint. NOTE: Fiberglass boats built this way do NOT have a gel coat yet. New to the scene, modern after-the-fact gel coats are available, but I have not personally used them. Any Fiberglass finish coat should be painted either with a gel coat type, or marine grade enamel (again follow the paint's instructions). But remember, fiberglass alone should have a protective paint applied in all cases.

Now for the real fun! Turning the hull right side up!

There was no other task more foreboding in my experience than trying to engineer turning a hull over with a minimum of manpower, and without the assistance of a crane! But take heart! It can be done! The most important thing is to THINK and PLAN! Most of the plans I have gotten from Glen-L and elsewhere, don't say a word about turning it over. Now I know why! There are no "right ways" to do it. Everyone takes a different tack. In my case, I loosen the building form from the floor and always turn the boat with the form INTACT. The reason is that the form adds considerable strength and rigidity to the boat. SO whatever method you come up with, you need to account for the form being there in any turning radius. On a small runabout, turning can be done usually with 4-5 people helping. One thing though, I would take a minimum of two 2x4x8's and temporarily clamp them from gunnel to gunnel about 1/3rd of the way from both ends. The excess portion of the 2x4 will then touch the floor first, NOT the edge of the gunnel, thus saving the gunnel and distributing the weight of the boat while on its side evenly over the whole structure. Before you turn the hull, make sure you have thought about where it will go once it's turned. Sounds real basic, but believe me, you won't want to start building some blocking to level the righted hull after you turn it. It's easier to do this while the boat is upside-down. I build long carpet padded "forms" that match the hull contour, and have these spaced out and installed into the floor area where the final work will be done. Remove the two lifting 2x4's and then remove the building form.

Hull space, encapsulation, flotation:

Once the hull is trued up, level and won't move on you, begin thinking about how you will finish the inside. This is very important because most wooden boats will take on plenty of water in regular use, to start dry rot immediately. You might as well do this job right. I believe that encapsulation with epoxy resin is the best all around method to use for ensuring that the interior will be dry, and non-accessible to water damage. But you have to think ahead (see I told you this was all about thinking and planning!). Some areas of the hull must be done now, before any thing else is installed. Once you close a space in, you hide it, and in essence have kissed it off to eventual dry rot! Take the time to carefully seal all wooden parts. Try to anticipate possible places where you might need to add glued members later for the cabin, or whatever, but it can be done. When the hull interior is sealed, you can now proceed on to the best part of the job, building the topsides to meet your unique needs. More on this in the next article! Good luck, and remember, I welcome any and all comments, questions etc.

Dick Koepp