16 ft plywood drift boat

[RichardJ]

I have acquired a 16-ft plywood drift boat with a rotten bottom and sides. I want to attach a new bottom and sides; how do I go about taking the old ones off and installing new ones? Where should I start---resheet one side first, then take the bottom off, or what...anyone with advice, please help! I was planning to use 1/4" fir plywood, is this a good idea? If you have different advice, I'd love to hear it. I don't want to use fiberglass if possible, but I do want to seal it above and below the waterline, any suggestions? Thanks for your help!

[gonzo]

I assume the framing is good if you want to replank. The method depends on how the boat was built. What is the planking made out of now? It may be a good idea to brace the frames as you take the old planking off so the shape doesn't change.

[RichardJ]

1/4"-6 mm marine plywood (don't know what type). Where the drainhole in the bottom of the boat is where it rotted and blew out. From what I can see, there are one or two frames that have rot damage on them. Other than that, all the frames are strong and the boat seems fairly sound. I believe when I dismantle where the bottom and the side meet, I will probably find some soft wood there also. However, I can't see any on the outside or inside of the hull in those areas.

[gonzo]

Can you just repair the rotted area without replanking the whole boat? It would be easier and cheaper.

[Bob Smalser]

rotten bottom and sides.

Any way you can post pics?

Anyway...if it were just the bottom you could add a sheer brace above the center thwart, cut any fabric, pry it off, replace it, and refabric.

But I suspect it's more than that...if the thruhulls weren't sealed correctly the side-bottom joint probably isn't either.

That means you need to build two molds...preferably according to the design plans or modified so that opposing frames are adjacent rather than superimposed over the molds...screw them vertically to spaced sawhorses with the molds notched for a string line to run down dead center...mount the boat on the molds, screwing the the adjacent frames to them.

Then bottom can be removed and sides evaluated for repair or replacement. If the frames are attached to the sides, you'll have to do them over, too, if you can't repair those sides.

Bottom line is if the sides are unrepairable, restoring the boat will be as much effort as building one from scratch.

I built one last summer that, while not a drift boat, is constructed in the same manner...note the yellow string line dangling fromt he sawhorses that's used to align sides to halfbreadth dimension. Here the laid-up cedar sides are temporarily screwed to the molds and the frames are already attached to the sides:











20 miles and a ferry ride away...let me know if I can help.

[RichardJ]

Here is a picture of my project...

[Bob Smalser]

Ok...the bottom's off...I'd get it up on sawhorses to even the stresses right away...I see what looks like a chine (side-bottom framing member) on the starboard side but bare plywood edge on the port side.

You can splice in new wood to and frame rot in place, or replace the frame...

...but what condition are those sides in?

[gonzo]

Are you willing to fiberglass the seams?

[RichardJ]

Here's a picture showing sideshell....As opposed to fiberglassing the seams, couldn't I just replace the bottom and side and seal the seams with 5200 during installation?

[RichardJ]

Obviusly, port side of boat needs a lot of work. Here is a picture of the starboard chine. Does this look like it would be salvageable, ie could I seal it with epoxy and refasten a new bottom to the chine and frames? Or should I just order a new Greg Tatman kit and use this boat to heat my workshop?

[gonzo]

5200 or sikaflex would work OK. It is better not to seal the wood with resin because the adhesive needs humidity to cure. One of the advantages is that it draws it from the wood. Adhesive caulks fill pretty large gaps, so fitting is easy. Also, they adhere so well that fasteners are only necessary to hold the panel in place until they cure. You can use the same system to fix the damaged chine log.

[Bob Smalser]

The boat looks plenty salvageable from here. As most of these are trailer boats, I'd guess it was rainwater and neglect that caused the damage. Bet the trailer had a flat on the port side and the water settled there.

I'd be probing with an icepick to determine location and depth of soft spots....either splice in graving pieces (patches) with epoxy after chopping out the rot or replace the entire framing member. Doug Fir heartwood is perfect for framing repairs in this boat.

Same with the plywood sides...any severe rot needs to be cut out and new plywood epoxied in before that port chine is replaced. Fill all the old nail holes on both sides while you are at it using your excess thickened epoxy.

Then you could certainly bed a new bottom to the chines in a poly adhesive like 5200. But I'd sure fasten it as it was originally as opposed to trusting the goo. That and rot pockets are what filling the old nail holes are about.

If the repairs to that port plywood side are extensive, then fabric and epoxy on top of that seam and atop those repairs may be a good idea for strength.

These boats hit a lot of rocks running those rivers and your repairs need to keep that in mind.