what would you suggest?

Designs for inboard or outboard power

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monkey
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Joined: Sun Jun 18, 2017 9:17 pm

what would you suggest?

Postby monkey » Sun Jun 18, 2017 9:43 pm

Hello,

New member and I will try and keep this as short and simple as possible. I am a flyfishing guide based out of Oregon and my father and I have been building a Hankinson design rogue runner. The plans suggest only to attach the 3/8 plywood sides to the sheer and chine and to not fasten them to the six frames as it will cause points of stress. The bottom is similar with it being only attached to the transom, longitudinal battens, and chine. We have followed these instructions but I am still torn, to me this looks like a water collection site with potential of rot. We tried to mitigate this as much as possible by treating wood that would be covered with multiple layers of epoxy, both the bottom and sides are fiberglassed as well. Frames are White Oak and gussets 1/8 epoxy treated plywood. These are what I believe to be my options.

1. leave it alone and trust water will drain and durability of white oak will withstand rot.

2. fasten from bottom and sides (even though glue is impossible between plywood and frames) and add epoxy fillets.

3. add only epoxy fillets to frames and hope stress fractures don't form and get into the air bubble between frame and plywood.

I am still really leaning towards keeping as is and trusting the durability of the Oak but just fear the sand and grit grinding that dark small space into rot central. Thanks for any insight.
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vupilot
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Re: what would you suggest?

Postby vupilot » Mon Jun 19, 2017 7:46 am

Youll be fine with everything encapsulated in epoxy.

BillW
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Location: Seattle, WA

Re: what would you suggest?

Postby BillW » Mon Jun 19, 2017 8:16 am

You are correct in that fasteners (screws or nails) were not used at the frames. Don't add them now, if that is what you are asking.

Possibly the limber holes (water drain holes) could have been larger, so they don't get clogged. Just check them occasionally in use.

It looks very nice.

JimmY
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Location: Brighton, MI

Re: what would you suggest?

Postby JimmY » Mon Jun 19, 2017 9:52 am

Hi Monkey,

If the edges of your frames were encapsulated before attaching the plywood skins, you should be okay. Your post seemed to indicate that you did multiple coats of epoxy. If you did not encapsulated them prior to sheeting, then you might have an issue.

The last thing you want to do is put fasteners through the plywood into the frames. Think perforations on a book of stamps. If you perforate the plywood in a high stress area (forward to backwards), you concentrate the bending stress at that point and risk cracking the plywood at the frame. Your boat appears to have a pretty gentle curve to the bottom so there should not be much stress at each frame. It should be okay to glue the plywood at the frame, since it will squeeze out and not introduce any additional stress in construction. Where you need to be careful is at a significant bend in the plywood if the frame is creating a hard spot and introducing stress. On my Squirt, the plywood is glued to frame 1 where the plywood is pretty flat or making a gentle curve. At frame 2 where there is a significant bend into the bow, there is a gap between the frame and side plywood and I made sure the bottom sheeting did not have a bump at the frame.

Keep in mind that you will probably be applying another coat or two of encapsulation epoxy to the entire interior of the boat before painting/clearing (for UV protection). This should seal up the frames to the plywood and keep out any grit.

I hope this helps.
-Jim
Nothing says poor craftsmanship like wrinkles in your duct tape!

TomB
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Location: Holland, MI

Re: what would you suggest?

Postby TomB » Mon Jun 19, 2017 3:02 pm

Hi Monkey,

No fasteners. I think you are also asking about the contact surface between the oak frames and the plywood skin. There are a lot of old wooden boats out there with a similar construction details that have lasted for generations so I wouldn't worry about it. I would suggest using stitch and glue type fillets to spread the load along the plywood and reduce the likelihood of cracking the epoxy in the corners if you are hoping to fully encapsulate the frames.

Tom

PeterG
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Joined: Mon Dec 03, 2007 7:08 am
Location: Connecticut

Re: what would you suggest?

Postby PeterG » Mon Jun 19, 2017 6:45 pm

Your concern is a good one. I read in Don Danenberg's boat restoration book that moisture and dirt in tight places is a big concern, will promote mold and rot. His fix with the old mahogany runabouts is to seal the wood with CPES which wicks into the wood and fills the grain, sealing moisture out. He beds all joints with 3M 5200 sealer too, for blocking out moisture and dirt. He get fantastic, long-lived results. We can follow his methods, and I also think that simply sealing/encapsulating will give similar results. As long as your frame edges were sealed/encapsulated or better yet glued to the plywood you are all set. If it was bare wood, I think encapsulating the interior like mentioned above will give good protection too. I will be using a combo of methods where CPES will be used for tight areas below the waterline and the underside of the deck, epoxy adhesive for attaching the planking to the frame edges, and epoxy for encapsulating below the sole (floor) inside the boat. The rest of the interior I hope to stain and varnish like the old runabouts.
Murphy's Law: Anything that can go wrong, will go wrong.
Griffin's Law: Murphy was an optimist.

monkey
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Joined: Sun Jun 18, 2017 9:17 pm

Re: what would you suggest?

Postby monkey » Mon Jun 19, 2017 9:39 pm

Thanks everybody for the responses. Thinking back on it both my dad and I are not completely positive the floor frames have epoxy on the underside, pretty sure but not for certain. If they were not the CPES sounds like a good option, for the application would you have to get to underside of frames? Or would it penetrate enough to be applied from the vertical faces? Curious to hear peoples experiences with this product.

thanks again! great to have a resource like this.

slug
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Location: Colborne ON Can

Re: what would you suggest?

Postby slug » Tue Jun 20, 2017 8:41 am

I went with CEPS to be certain in these areas. It's reasonably inexpensive (compared to epoxy) and you can really soak it on. Use good ventilation though as it isn't good for you.
Doug


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