First stitch and glue project

Hi guys,
I am currently in progress of my first build, a McKenzie river stitch and glue. I have been researching this project for several months and been working for a couple of weeks. I have been pulled in a hundred different directions and don't know what to do. Sidewalls are stitched and the inside of the boat has 2 coats of epoxy. I will ask some questions and if anyone can help I would really appreciate it.
1: Would a chine log on the inside of the boat benefit me over a fillet? I was told this would increase strength.
2: If this chine log would help, can I use my 1/4" plywood and laminate the chine log?
3: My plans apparently did not call for any rocker. I did not know this until the boat was stitched together. Is there any way to add rocker other than taking the sides apart and re-cutting? I messed around with spreading the topsides to get rocker but this worries me structurally.
4: The plans I have call for one 5 oz glass layer on the outside bottom of boat. This seems light to me so I ordered 5 oz Kevlar for the bottom and by reading on here sounds like I need several layers on the bottom if using 5 oz. Any comments on this?
5: Finding proper lumber for me in central Indiana has been a struggle. If I use cedar and cypress, would I have any problems? This wood is for bulkhead cleats, gunwales and possibly the chine log if plywood is not acceptable. Can I rip a 16’ 2X by myself on a table saw?
This is just the tip of the ice berg. Any help would be greatly appreciated! Apparently my plans weren’t quite as thorough as I thought.
Thanks,
Joey

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Permalink Reply by Phillip Westendorf on April 19, 2013 at 5:07pm

Joey,

Sound like fun, good luck with the Gobblers.  FYI, here's my "Moaning Chair".

 

Dorf

Permalink Reply by Rick Newman on April 19, 2013 at 7:56pm

Dorf I like your magnetic welding jig! I have two chairs, the are both old office chairs, the first one doesn't have a back anymore and is rather low allowing me to wheel around the boat and sand and sometimes paint. The second is fancier and I can recline when I really need to solve a problem. If I had any of your boat building lubricant in the evening I would probably fall asleep. Coffee powers a lot of sanding strokes!

Rick N

Permalink Reply by Eric Loudenslager on April 17, 2013 at 7:19am

Since you are building a stitch and glue boat epoxy was the correct application for interior sealing. Stitch and glue boats need to encapsulate the plywood and prevent water infiltration. Even if you did not use glass with the epoxy, the boat should be sealed.

Epoxy coating is not UV resistant and will break down over a couple years. To protect the epoxy it needs to be topcoated with a UV protectant. Boat soup will not be sufficient. The typical choice is paint or varnish. I use paint. Lasts longer. Varnish needs to be refreshed every year. The UV essentially consumes the varnish. Paint should last a decade unless the boat is used everyday. If you do not have a garage or barn for your boat get a good cover to keep leaves and water out.

Any paint will do, but they all have different characteristics. Latex house paint is soft and not often used in backyard boats. Next up is alkyd hardware store porch paint, followed by alkyd marine enamel. I tested some Benjamin Moore alkyd porch paint a year or so ago and found it unsatisfactory compared with Interlux toplac (no longer available) and Interlux brightsides. The BM never seemed to really cure (stayed soft) and in comparative sanding experiments was removed an order of magnitude faster than the Interlux. Check out the Jamestown Distributors video comparison of hardness, cure time, and leveling for Epiphanes, Interlux, and Petit.

The downside to these alkyd paints is the use of various solvents for cleaning and thinning, plus you either need to clean brushes and rollers or throw them away after one use. Ultimately though, the paints are suitable.

Next up in cost and application challenge is System 3 waterborne LPU. No solvents, expensive, you can re-use brushes and rollers. Application is a bit touchy, especially in high temps and low humidity. Two-part formula.

Finally, there are two-part solvent based LPUs from Epiphanes and Interlux. I've never used them. They are hard, expensive, and do not seem to be used much by homebuilt driftboat builders.

My current project is refinishing kitchen cabinets. They are being painted with waterborne acrylic from General Finishes (they call it Milk Paint, but it isn't). A crosslinker can be used, and the paint is suitable for exterior furniture, kitchens, and baths. It needs to be topcoated with a clear final finish. I'm thinking this may be suitable for a backyard boat. I'll be making up some test panels in a few weeks and leave them outside and see how they hold up to rain and sun.

Good luck with your choice. There is no perfect solution.

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