Dufour Owners Association: new forum reply to Questions about hull construction, throughhulls/seacocks & compression post (Dufour 36 Classic, but probably applies to other models as well)

New reply from Arik Nativ

<p>Hallo Robert,</p>
<p>This is how its done on my 41 Classic from 2000.</p>
<p>Its a light weight Ball Valve, free from corrosion and electrolysis made by Trudesign.</p>
<p>For your inspiration ;-)</p>

https://www.dufour.org.uk/members-forum/questions-about-hull-construction-throughhulls-se

Original Post by Robert Buhrke

Questions about hull construction, throughhulls/seacocks & compression post (Dufour 36 Classic, but probably applies to other models as well)

<p>Dear fellow sailors,</p>
<p>Sorry for the longer post, and some questions which may sound stupid. We are very new to the Dufour 36 Classic and wondering if anyone can please share information about:</p>
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<ol>
<li><strong>The hull: Is it a sandwich construction (with a foam- or other core material), or a solid (single skin) GRP hull?</strong> <br />Initially I thought these were solid (based on various descriptions), but after having a closer look I suspect its a sandwich construction, so just looking for confirmation here. Are there any know problems, or weak spots with the hull or coring?</li>
<li>I noticed the hull is substantially thinner in most places where through hulls & seacocks have been installed. (See attached photo.) <br />Is this a normal way how Dufour installs through hulls (e.g. to avoid problems with leaks into the core/sandwich construction)?</li>
<li><strong>Has anyone installed – or would anyone recommend installing) extra backing plates, to strengthen areas where seacocks are installed?</strong><br />PRACTICAL-SAILOR.COM (Feb 2019 issue) recommends backing plates for thin hulls, and I wonder what you think of this approach?<br />A great article has been published here: https://www.practical-sailor.com/systems-propulsion/seacocks-for-thin-hulls</li>
<li><strong>What brands/types of throughhulls and seacocks would you recommend?</strong><br />I know that I should look for bronze, DZR (or DR)-marked parts or ABYC approved reinforced plastic (e.g. Marelon) which seem appropriate, but can you recommend some good brands? Also wondering if anyone has longer-term experience with these ones? https://www.trudesign.nz/marine/certifications/1-seacocks-and-through-hull-fittings</li>
<li><strong>The compression post: Is this solid timber, or is there any steel or other material inside that may corrode if water gets in?</strong></li>
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<p>The boat is a 36 Classic from June/July 2000, hull number 176.<br />Any advice and recommendations would be greatly appreciated, since we're planning repairs & some replacements.</p>
<p>Many thanks in advance!</p>
<p>Kind regards, <br />Robert</p>