Towing eye

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Towing eye

Nigel McC
Has anyone added a towing eye to the stem? I may tow the completed dinghy behind a larger yacht, I am reluctant to tow from an eye fixed transversely through the stem or the false stem, as the intermittent shock load would likely delaminate the timbers. I can see that a transverse fixing would suffice for a bowsprit brace.
Nigel McC
Hamilton
New Zealand
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Re: Towing eye

PaulW
Administrator
Hi Nigel.  Interesting question, definitely deserving wider and careful consideration.  
You are likely to get useful comment from Francois Vivier.  Ask him.
I'll postpone my response till I've given it more thought.
Meanwhile ...
Any Morbiceeres out there got any relevant experience or thoughts?
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Re: Towing eye

Portnastorm

Hi Nigel.
I don't tow my boat but I do like to have an eye low down on the stem, mainly to lash it to the trailer. I use a stainless eyebolt fixed longitudinally through the stem. I think its 8mm diameter with a big washer under the nut.  I had already cut a section out of the central vertical frame in anticipation of fitting this. This is a very strong point on the hull with any shock loads being spread through the stem and bulkheads. I would think the most likely point of failure would be the eye-bolt itself so I'd go large. Maybe an anchor snubber on the tow rope would smooth things a bit.
Regards, Graham.  
Graham Neil https://port-na-storm.blogspot.com/
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Re: Towing eye

PaulW
Administrator
It is encouraging that Graham has endorsed the concept of the eyebolt through the stem.  (He has built a boat or three)
In the Swefn videohttps://www.youtube.com/watch?v=eojnXZ_MtA0 you can see their detachable bowsprit is constrained by a bobstay attached to an eyebolt.  Viviwer's "Plan 54" the "Etrave 5 plis, Stem 5 layers" seems to me to offer a lot of strength, bolstered by 10 (or in our case 11) laminates of false stem, plus the rubbing band.

The bowsprit on Proteus is restrained in a "Bowsprit iron" mounted to the stem.
The lashing arrangement on Proteus is much simpler.  We have a transverse hole through the false stem, lined with a bell-ended copper tube, but like Graham we use it only for security on the launching trolley/trailer.

'Elf Warning - The above is the perspective of an engineer not a boatbuilder.
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Re: Towing eye

Nigel McC
In reply to this post by Nigel McC
Thank you Paul, Graham and Morbic people,
Reassuring to know others have been down the same track.
Graham’s design is more or less what I was planning, that is a s/s eyebolt fixed longitudinally through the stem, fixed in a cut out in the central panel, and with a cut to size s/s washer on the inside to spread the load; just above the water line seems the right place. That means that any tow tends to lift the bow, rather than bury it.
I have previously fitted an eye to an Oughted Auk, (see photo) and it tows beautifully.
We are planning an expedition out to Great Barrier, about 22 nm, but across the Colville Channel.  And it would be good to take the Morbic if I finish in time.
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Re: Towing eye

PaulW
Administrator
More about Towing-eye.
A parallell topic was started in Mar 21, 2021 by Marc Lein -  See "Eye Bolt"