Wooden Boat People

By McKenzieDriftBoat.com

Questions about installing a UHMW shoe

Greetings - new member here, as well as a new boater. A few questions for the pros:

My buddy and I are installing a 1/4" UHMW shoe on a 17' Tatman (yes, even after having carefully reviewed, here and elsewhere, the pros and cons of doing so). It is going over a layer of West epoxy/graphite. Here are my questions:

1. Will it make any structural or functional difference whether the 4x10 UHMW sheets are installed lengthwise with the 10' pieces running the length of the boat with separate triangle sections fore and aft (or bow and prow.....or transom and prow.....I acknowledge the terminology issue), or sidewise, installed perpendicular to the boat in multiple 4' sections?

2. We intend to countersink 1" screws seated in 3M 5200 along the chine and across the ribs. Should we use standard SS flat-head wood screws, or some other type of fastener?

3. We are thinking of adding a strip of the UHMW over the existing oak chine batten. Should that be installed so that the UHMW bottom overlaps the edge of the batten, or installed so that the batten overlaps the side edge of the UHMW bottom? Does it really matter?

4. Please let me know if by my very questions I have demonstrated a fundamental misunderstanding about anything significant.

Thanks - the information gathered as a lurker as been tremendous.

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Replies to This Discussion

Permalink Reply by Phillip Westendorf on January 7, 2014 at 5:13pm

Russ,

I might not be the best person here to answer your questions but here's my two cents worth.

1. If it was me I would secure the bottom piece lengthwise with a few joints as possible.. Move the 10' pc forward and add a second piece aft of it. I'd machine a lap joint between the two pieces, about 1/8" deep and 3/8" long. Minimum gap fore and aft (approx. 1/32"). Might goop it here good with 5200 too.

2. I think 1" screws are a bit short. I'd use at least a 1 1/4" long screw maybe a 1 1/2". Flat heads will be fine, anything else would require a counter bore to sink the head flush and reduce the material's strength.

3. I would have the chine batten partially over lap the bottom plate, about 3/16" of the 1/4" bottom thickness. Any impact loads (like hitting a rock, stump, etc.) will impart loads to the chine and distribute forces along the chine. If the load were to strike the bottom's edge directly (the bottom plate extending to the outside edge of the chine covering's UHMW piece) the force would put the screws holding the bottom plate on would be in shear. This would add to premature screw failure. Leave a small gap between the edge of the bottom and chine cover and goop it real good.

Hope this helps, G'LUCK

Dorf

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Permalink Reply by tungsten on January 7, 2014 at 7:23pm

Hi and welcome,

Generally things that exspand and contract need some sort of sliding joint,one over the other or leave a gap and fill it with something flexable.