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Re: boat plans

Posted: Tue Jan 18, 2022 9:45 pm
by DetroiTug
Quote: "'18 gage mild steel sheet, primed on both sides. In service, it is constantly exposed to high humidity from the cylinder cocks. It rusted through in four years.''

Primer of the spray bomb variety is the worst protective coating there is, it's porous and holds moisture.

If steel is sandblasted prior to paint, and good quality marine primer and topcoat is used, it will last for many years. The vast majority of surviving hulls of antiquity are steel. I work with 120 year old cylinder cladding and yes it's still viable, but it's been rusted over and the surface is loaded with tallow. These modern steam cylinder oils being suggested are not rust inhibiting. They can print ''SCO'' on the label, but if it does not contain tallow it's not steam cylinder oil. These little 120 year old car engines I work on, nothing is ever rusted together, all bolts loosen as they should, because of the tallow soaked in every crevice, has nothing to do with the steel. Linseed oil will do the same thing.

Re: boat plans

Posted: Tue Jan 18, 2022 10:07 pm
by barts
If steel is sandblasted prior to paint, and good quality marine primer and topcoat is used, it will last for many years.
For those w/o access to sandblaster, I've found that brushing on phosphoric acid and letting that dry, then rinsing & wiping makes a good surface for paint. The best paint I've used for painting steel is a metal-filled moisture-cured polyurethane, but this can be hard to find. Industrial Rustoleum works as well, but isn't as hard.

- Bart

Re: boat plans

Posted: Tue Jan 18, 2022 10:29 pm
by DetroiTug
Quote: "brushing on phosphoric acid and letting that dry,''

Vinegar works well to improve adhesion also.

With the sandblasting it's mostly about removing the millshale from hotrolled steels. After working in and around steelfab many years, rarely was anything sandblasted prior to paint, never a considerable issue. These were components outside in Michigan winters.

This the best rattlecan spray paint I've ever used

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Ron

Re: boat plans

Posted: Fri Jan 21, 2022 3:13 am
by fredrosse
The Margaret S steamboat hull is very similar to the Shelway Fisher Sapphire. 19ft-3in x 60in for Margaret S vs 19'-1" x 59in for the Sapphire. A rather narrow beam allows somewhat better speed than many wide beam type boats. I will share these plans if you like. As far as building, with a full time day job, a friend and I built the hull in about 6 weeks, 1/2 marine ply sides, 5/8 marine ply bottom, all fiberglass and epoxy covered, and metal hull construction could be used. The steam plant took far longer to build.

I have also converted fiberglass sailboat hulls to steamers. Cut out the centerboard well, fiberglass in a shaft tube made from PVC pipe, and there you have a hull ready for the steam plant. About 40 hours work and a few hundred dollars all-in cost to get a fiberglass sailboat hull ready for a steam plant. Last summer I put a rather large steam plant into an O'day Javelin planing sailboat hull, The Javelin is small at 14 feet length, and some other fast sailboat hulls would be better.
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I have considered the
O'Day Daysailer quite ideal (17 ft), with 12,000 hulls built. Other options include:
The Thistle, 17 feet. look up an excellent conversion on this forum, about 4000 hulls built.
Flying Scott, 19 feet, 6000 built
Lightning, 19 feet, over 15000 built, a fast hull with plenty of room for a larger steam plant. I wish I had bought one of these that was available, with a broken mast and a good trailer for $250 a few years ago.

Re: boat plans

Posted: Fri Jan 21, 2022 3:45 am
by RNoe
Steam Thistle Cluaran here:
viewtopic.php?f=4&t=2211
RussN