Delaying Glen-L 15 build, starting a Zip

Outboard designs up to 14'

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Woodbot
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Delaying Glen-L 15 build, starting a Zip

Post by Woodbot » Tue Jul 16, 2019 11:55 am

Good afternoon,

Joined a few years ago to start building a Glen L 15. Life happened and finally got around to doing it. Unfortunately, family is more intersted in a powerboat for skiing/tubing than sailing. As such, Zip plan arrive tomorrow and I've been soaking up as much info as possible from Glen-l forum members and youtube over the last few weeks.

Overview of Zip Utility build:
- Frames/20" Transom/Keel/Battens from sapele or mahogany, whatever has 16' lengths to limit scarfing. Have lots of ash available but not going to use
- Chines, Sheers from southern yellow pine heartwood (if available, otherwise sapele/mahogany). Considerably easier to bend. Will likely laminate
- BS1088 marine plywood, will be painting entire hull so grain doesn't matter. Will also paint majority of interior except dash and few select other areas.
- Flooring/Decking from cherry, possibly intermixed pattern with SYP.

First question I had was regarding encapsulation/glassing the hull. After reading Boatbuilding with Plywood and the West Co book on boatbuilding I came across "The Complete Wooden Runabout Restoration Guide" by Don Danenberg. He advocates CPES (semi-permeable) + non-permeable barrier over the hull, with use of CPES in the interior with 3m 5200 for bedding joints instead of non-permeable epoxy covering the entire boat. The semi-permeable membrane on the interior allows for wood to appropriately release moisture, thereby preventing future rot. This is similar to homebuilding where vapor barriers are spec'd on only side of the house to prevent mositure from being traped within the walls and rotting the studs.

Love to hear thoughts on this. Thanks and I look forward to posting my progress.

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vupilot
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Re: Delaying Glen-L 15 build, starting a Zip

Post by vupilot » Tue Jul 16, 2019 1:32 pm

Sounds like a good plan. You've been paying attention.

CPES and 3M 5200 seem to be the way to go on restorations. On new builds I think epoxy is just fine and will prove to last. More than what products you use on it, how you store the boat will determine its longevity.

Keep us posted and enjoy your build!

TomB
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Re: Delaying Glen-L 15 build, starting a Zip

Post by TomB » Tue Jul 16, 2019 2:32 pm

Woodbot wrote:
Tue Jul 16, 2019 11:55 am

First question I had was regarding encapsulation/glassing the hull. After reading Boatbuilding with Plywood and the West Co book on boatbuilding I came across "The Complete Wooden Runabout Restoration Guide" by Don Danenberg. He advocates CPES (semi-permeable) + non-permeable barrier over the hull, with use of CPES in the interior with 3m 5200 for bedding joints instead of non-permeable epoxy covering the entire boat. The semi-permeable membrane on the interior allows for wood to appropriately release moisture, thereby preventing future rot. This is similar to homebuilding where vapor barriers are spec'd on only side of the house to prevent mositure from being traped within the walls and rotting the studs.
Here's my two cents...

The key word regarding Danenberg is "Restoration". He is dealing with boats made from lumber and covered in paint or varnish. It is important to let the water out if it's in there and in a painted/varnished boat it's in there. He uses 5200 which allows the lumber to expand/contract (read change moisture content) without breaking the bonds.

The difference between modern house wrap and CPES is important. Wrap is a one-way vapor barrier, it lets moisture out by not back in. CPES allows moisture to move both ways.

Build a new boat with kiln dried lumber and plywood and different options become available. Encapsulate liberally inside and out, and the moisture content within the hull will stay steady for a really long time, minimizing expansion/contraction and the chance of rot. Dings, dents, and the encapsulation spot that was missed are like tears in vapor barrier and need to be repaired to keep moisture out. Glassing the wear areas on the hull will help to prevent holes in the vapor barrier.

Tom

Woodbot
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Re: Delaying Glen-L 15 build, starting a Zip

Post by Woodbot » Tue Jul 16, 2019 6:33 pm

vupilot - thanks. I'm going back through your entire build via blog trying to learn all i can before starting. any reason you decided to plank the sides and then do the battens as opposed to planking the entire hull at once?

TomB - you and vupilot both pointed out the restoration aspect, which i appreciate. I was looking for failure points and figured those fixes might improve my project if used at the front end. However, I also understand how modern technologies can make up for my amateur boatbuilder status (i.e. just like framers series studs obviate the need for a carpenter who understands crowns). Interestingly, Dan points out his use of CPES and 3m 5200 on new wood, but I assume it's part of a restoration where he's mixing higher moisture content wood (i.e. old) with new and requires a more flexible system. Steve Smith (CPES inventor) has a blurb discussing why CPES is good for new wood, focusing on the ability of semi-permeable membrane to equilibrate vs an epoxy system that cannot, possibly leading to cracks at the wood-epoxy interface that allow influx of moisture. But he's also trying to sell CPES.

EDIT: Dan does submit that epoxy encapsulation can be performed in brand new builds using thinner planking materials (1/4" ply probably counts) when built in a temperature and humidity-controlled shop and maintained diligently against trailer dings, scratches, etc. Exactly what TomB said. The "enhanced traditional" bedding method promoted by Dan also requires diligent maintenance so probably will stick with the epoxy.

As with my prior projects, I'm likely overthinking something that should be fun for me and my kids. Thanks again for the input.

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hoodman
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Re: Delaying Glen-L 15 build, starting a Zip

Post by hoodman » Tue Jul 16, 2019 7:59 pm

Woodbot wrote:
Tue Jul 16, 2019 6:33 pm
As with my prior projects, I'm likely overthinking something that should be fun for me and my kids. Thanks again for the input.
Go with Glen-L's recommendations and you'll be fine. These boats are fundamentally different than the strip planked hulls likely referred to in the restoration texts.
Matt

Building a Geronimo......!
viewtopic.php?f=2&t=25139

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BarnacleMike
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Re: Delaying Glen-L 15 build, starting a Zip

Post by BarnacleMike » Thu Jul 18, 2019 10:55 am

Fundamentally different, and in NO way inferior.

If you look at boat construction methods from most 1950’s era runabouts, they were using long-established techniques that were becoming dated. Glen’s designs were cutting edge for their day.

As noted... restoration of a classic is an entirely different matter than a ground-up build.
-Michael

"How long does it take to build a boat? Until it's finished" — yours truly

Blog (Utility & Zip): http://barnaclemikeboats.blogspot.com/
Website of Boat Photos: https://michaelsmaddox.wordpress.com

Woodbot
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Re: Delaying Glen-L 15 build, starting a Zip

Post by Woodbot » Sat Jul 20, 2019 9:48 am

Thanks again everyone for the input. Going to follow the instructions and epoxy/glass hull, epoxy/paint interior and epoxy/varnish deck. Transferred plans to template ply; just waiting for marine ply and mahogany to start the frames.

As I surveyed tools I wondered about using a 12" disc sander to create 10 and 12 deg bevels. Anyone do this?

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BarnacleMike
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Re: Delaying Glen-L 15 build, starting a Zip

Post by BarnacleMike » Sat Jul 20, 2019 3:53 pm

As for the outer surfaces of the frames, it is just as easy / simple to make 90 degree cuts and worry about the bevels later, during the fairing process.

MY perspective is that it’s more important to make the 12 degree beveled cuts in the batten notches. I did this with a multi-tool, and a wood block with a mating -12 degree bevel that I clamped on & used as a guide.
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-Michael

"How long does it take to build a boat? Until it's finished" — yours truly

Blog (Utility & Zip): http://barnaclemikeboats.blogspot.com/
Website of Boat Photos: https://michaelsmaddox.wordpress.com

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BarnacleMike
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Re: Delaying Glen-L 15 build, starting a Zip

Post by BarnacleMike » Sun Jul 21, 2019 8:49 am

Just to clarify about the pictures...

I am using a slightly different method to build my transom than the method mentioned in the Glen-L instructions. The instructions call for 1” solid lumber frames mounted to 3/4” plywood, with the notches cut only in the solid lumber.

I have 1” solid lumber frames mounted on 1/2” plywood, and as shown, I cut the notches all the way through. I will later add an additional layer (or two) of 1/4” plywood to complete the transom thickness and cap the ends of the battens.
-Michael

"How long does it take to build a boat? Until it's finished" — yours truly

Blog (Utility & Zip): http://barnaclemikeboats.blogspot.com/
Website of Boat Photos: https://michaelsmaddox.wordpress.com

Woodbot
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Re: Delaying Glen-L 15 build, starting a Zip

Post by Woodbot » Sun Jul 21, 2019 1:57 pm

Good idea on creating that bevel. I like simple ways to handle finesse aspects of the build.

Upon reviewing your blog and seeing the number of scarf joints required due to wood length, I went ahead and built a jig for the table saw. Stole the idea from youtube and made some modifications. Used a MicroJig mounted to a 1/2" piece of scrap plywood. Transferred 5 deg, 10deg and 12 deg angle lines to the board, counterbored some holes and fixed in place. Worked better than I thought.
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Woodbot
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Re: Delaying Glen-L 15 build, starting a Zip

Post by Woodbot » Mon Jul 22, 2019 4:19 am

I'm building this Zip as a utility. Planning to keep dash at frame 4 and moving seat up 12" from standard runabout position, excluding the rear cockpit deck. Should I build frame 2 without the top member, or build it with top member and then cut when I run the carlings and blocking? I'm leaning towards the latter just for lateral stability through the hull construction and flip.

Woodbot
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Re: Delaying Glen-L 15 build, starting a Zip

Post by Woodbot » Wed Jul 24, 2019 5:37 pm

IMG_20190722_164958898.jpg
Started with 26 board feet of sapele (12' length x 13" wide x 8/4)
IMG_20190722_193109823.jpg
After putting on a formal straight edge, planing, ripping and tracing all frame pieces I was left with this.
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I've now completed resawing and replaning all boards down to net 7/8". Time to screw together and run through the bandsaw, staying just proud of the template line. Then I can trace out my gussetts and start gluing frames together.

Sapele has been rather hard on my tools. Think I'll use mahogany for the keel and batten. Definitely using pine for chines and sheers. Still using the large amount of dried cherry I have for deck and flooring.

Woodbot
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Re: Delaying Glen-L 15 build, starting a Zip

Post by Woodbot » Thu Sep 05, 2019 4:05 pm

Been a while since my last update. Had a 2 week break doing yard renovation. Hoping to drill keel-stem and keel-knee-transom for dry fit tomorrow, then epoxy. Got 16' pine boards for the sheer and chine so hope to spring those in the next week with a steamer and 6mil plastic. Pine boards only 3/4" so I'll have to rip, plane and laminate sheets and chines. Extra epoxy and clamp time wasn't what I wanted, but oh well.
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