Walking the dog back

It looks like the top fabrication part of this project is in the home stretch. The paint has been ordered and is on its way here. The unpainted top is sanded and my friend Major and I moved it out of the shop and into the carport yesterday. I went through the shop with a leaf blower twice, moving clouds of epoxy sanding dust out of the soon-to-be paint shop. I looked like a snowman after the second pass and I still have a strange taste in my mouth, despite the dust mask I wore during the blowout sessions.

The plan is to let the remaining dust settle, then move the top back in and roll on two coats of two-part epoxy primer paint. (The working attire will include respirators).

Meanwhile, I think it might be interesting to take a brief look at the thinking behind three major decisions. These were: Marine plywood substrate construction versus molded or formed fiberglass lamination; epoxy versus polyester resins, and two-part versus one-part polyurethane paints.

Back when I did process analysis, we would often take a project apart after the fact to see what worked and what didn’t work. We called this “walking the dog back.”  We looked at the key decisions and whether they were good or bad relative to outcomes.

This is my companion Gladstone, who often observes boat work around the place, usually from an up-wind and relatively dust-free vista.

Gladstone was once a celebrated adult professional at a puppy farm. He is now retired.

The Wood Decision

I had been thinking about doing this project for a very long time. I studied various ways to build boats with resins and fiberglass. I learned what is involved in building molds and forms and laying up resin and fiberglass to make rigid shaped structures. I decided this approach would demand levels of skill and patience I do not possess.

Later, I explored a number of wood boat building sources, finally zeroing in on how to make small wooden boats and canoes using the stitch and glue method. Often, these boats are made of marine plywood encapsulated in fiberglass cloth and resin. This looked like a good approach and something I could do, so that’s how I decided on a plywood substrate.

Epoxy

Polyester resin is less expensive than epoxy resin. Colors can be mixed with polyester resin, in some cases obviating the need for painting. Polyester is more resistant to sunlight’s ultraviolet radiation than is epoxy. 

But, polyester resin will not penetrate wood.

Epoxy resin, on the other hand, can send viscous tendrils into underlying wood fibers, increasing its bond to the wood, and the strength of the structure. That attribute, plus the fact that I have had some experience working with epoxy resin, were the main factors in the epoxy decision. 

Two-part polyurethane paint

I had been planning on using a one-part polyurethane paint. Going to two-part was a last-minute decision, prompted by an old boatyard hand who pointed out that two-part polyurethane paint delivers a harder, more reflective and more durable result.

Keeping water out of the vulnerable underlying plywood  is the key to a long and useful life for this new top. The epoxy moisture barrier has to be protected from ultraviolet solar radiation. Deciding for the best paint available for DIY application was a no-brainer. I haven’t worked with this stuff before. I will report on how hard or easy it is to use in my next post.

This project has aged Gladstone considerably. He will be very happy when it is over.

In summary

Those are the reasons for the key decisions. Whether they are the best decisions will become known in future years. I am confident. And I am looking forward to getting back on the water some time soon.

And next week...

...unless some major wheels come off, the priming and painting should be completed. After that, I will be recruiting some strong and agile friends to help maneuver the top down the ramp and into position on the dock alongside the boat.  We will do a trial fitting to the framework on the boat before we glue and bolt it down for keeps.

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