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Projects - Glacier Boats of Alaska boat projects / Re: 28 GA in Pagosa Springs colorado

« Last post by Brian.Dixon on Today at 06:30:17 AM »

Day three on the water. Raised the motor 2 inches, gained 500 RPM, way more then expected. Up to 5500 RPMs and happy with that at 7000 feet elevation. Last week I felt like the the back of the boat was pulling down, it was. I was getting water in through my scuppers when I would turn. Today no water in the scuppers. 37 MPH. More then I need most of the time.

Yup ... all boats are a teeter totter around the center of gravity.  Trim the bow up and the stern goes down and vice versa.  If the motor is too deep in the water, then you've got an undesired trimming up of the bow ... Note that when a boat is on plane, the center of gravity is above the waterline (around 9" to 12" in a Great Alaskan).  In an ideal world, you'd have the line of thrust (prop) at the same height as the center of gravity, but that's impossible when on plane.  The deeper the motor, the more leverage the motor has on boat trim.  The higher you can run the motor, the better ... as long as you are getting cooling water pick-up in all conditions and operations (hard turns) and your prop is not cavitating (including jamming the throttle on slow speed hard turns - aka 'evasive maneuvers' when you need that thrust!).

Brian

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Projects - Glacier Boats of Alaska boat projects / Re: 28 GA in Pagosa Springs colorado

« Last post by Djeffrey on August 04, 2020, 07:33:02 PM »

I forgot to mention that two hundred of that RPM came from trimming the engine up

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Projects - Glacier Boats of Alaska boat projects / Re: 28 GA in Pagosa Springs colorado

« Last post by Dan Boccia on August 04, 2020, 06:20:29 PM »

Wow! Going up 2 holes gained you 500 rpm? That's more than I would have thought too! I would say you've got the engine height set about right and the prop is just about right, congratulations! That must feel good.

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Projects - Glacier Boats of Alaska boat projects / Re: 28 GA in Pagosa Springs colorado

« Last post by Djeffrey on August 04, 2020, 06:10:05 PM »

Day three on the water. Raised the motor 2 inches, gained 500 RPM, way more then expected. Up to 5500 RPMs and happy with that at 7000 feet elevation. Last week I felt like the the back of the boat was pulling down, it was. I was getting water in through my scuppers when I would turn. Today no water in the scuppers. 37 MPH. More then I need most of the time.

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General Discussion about the Great Alaskan / Re: Bob from Olympia, 28 GA build

« Last post by Brian.Dixon on August 04, 2020, 04:13:08 PM »

Thanks for the link!  I shared it on FB...

Brian

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General Discussion about the Great Alaskan / Re: Bob from Olympia, 28 GA build

« Last post by Rbob on August 04, 2020, 11:58:24 AM »

That is one of the benefits of using peel-ply, if amine blush occurs it occurs on the outside of the peel-ply and no sanding or minimal sanding on seams for example.

I almost wish I had used peel ply after the 3rd coat of epoxy but it was 10:00pm when I put on the second coat.

Linky: https://epoxycraft.com/westsystem/using-peel-ply-to-best-effect/

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General Discussion about the Great Alaskan / Re: Bob from Olympia, 28 GA build

« Last post by Brian.Dixon on August 04, 2020, 10:38:07 AM »

You already know about making sure there's no residual amine blush before adding more epoxy, so I won't mention that ... but you know, subsequent coats of epoxy just need to have the shine removed from the previous coat (unless the prior coat is newer than 36 hours old, plus or minus).   You can take the shine off, without removing epoxy that you want to keep, by just lightly scraping ridges, specks/bugs, bumps off first then put your random orbital on top of a green scrubbie and 'sand' the epoxy.  The random orbital sander does a great job of scrubbing epoxy with a green scrubbie ... takes the shine right off without actually sanding.  Folks not using peel ply may have more of a weave pattern left that needs to be filled, so sanding helps ... green scrubbies alone may require more fill coats to get it all smooth (MY opinion is that the only smooth, shiny, faired surfaces should be those between the waterline and sheer, the exterior faces of side panels, and maybe the roof of the cuddy ... all else is OK to see a fiberglass pattern on).

Brian

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General Discussion about the Great Alaskan / Re: Bob from Olympia, 28 GA build

« Last post by Rbob on August 04, 2020, 07:50:34 AM »

What is amazing is the almost invisible seam the peelply leaves behind.  There is a seam where the glass overlaps that I will scrape / sand before adding last coat of epoxy tonight.

First pic is peelply on part of the roof, second one showing peelply seam which was hard to capture on pic.

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General Discussion about the Great Alaskan / Re: Bob from Olympia, 28 GA build

« Last post by Brian.Dixon on August 04, 2020, 07:33:41 AM »

Good plan. Use that 3rd coat.  It's not that much material is removed by scraping and sanding, noting that you should lightly sand even after using peel ply, but more about the thickness of the epoxy resin itself.  I doubt you'd end up with any too-thin regions after glassing, especially with peel ply, but for the cost and effort, why not?  Pilothouse roofs end up storing stuff ... fish nets and gear, rafts, etc ... it's a good area to protect with glass, epoxy, paint...

Brian

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General Discussion about the Great Alaskan / Re: Bob from Olympia, 28 GA build

« Last post by Rbob on August 03, 2020, 05:41:23 PM »

I will add one last coat of epoxy as Brian suggests, I know without peelply  you do the initial glass wetout, add a fill coat, scrape sand etc and add a 3rd coat.  The fill coat is to basically fill the weave and a topcoat for protection.  How much gets sanded away is a guessing game.

I think with a digital caliper one could do 2 test panels of the same thickness and compare peel-ply 2-coat vs 3 coat sanded/scraped epoxy  and/or make the panels exact same size and weigh the samples before and after the coatings. 

I may give this a test, and report the findings.