Upgrading Thru-Hulls & Valves on a (Beneteau) Production Boat?

[jbmia]

I have a 2005 Beneteau 323 with original thru-hulls and valves over here and I've read all the details on dezincification and given the age of these, I'm looking to replace (upgrade) them soon with either Trudesign's Marelon product or Groco's IBVF Flange adapter + Valve Combo... I've read Maine Sail's content on using backing plates and uprading to seacocks or groco's flange adapter, but I'm struggling with a couple issues I'd like some feedback on:

The first issue is Beneteau's matrix liner.... The thru-hulls under the galley sink only have liner cut outs just large enough to fit the thu hull and nut in the original install with no backing plate. Looks like my only option to upgrade to a proper install is to cut away the liner to make room for a proper backing plate. Would appreciate feedback from any production boat owners that have tackled this task...

The other challenge is over in the head underneath the sink cabinet. The shape of the hull and the liner offer very little room to actually install a backing plate. See pic below. Here the liner begins a sharp angular rise just to the right of the thru-hull / nut and it would appear that I don't have room to install a backing plate of the size needed to fit the Trudesign valve or a Groco IBVF Flange Adapter without cutting into that rise to the right. What would the experienced folks here recommend? FWIW, this one's actually a 3/4" thru-hull.

Here's another one... this is a 1 1/4" thru-hull / inline value that includes a 45 degree elbow between them.. I'm pretty sure these are all original.. I have the same issue with lack of room for a backing plate, but also a likely challenge getting a properly installed valve in there without the 45 degree adapter. Following two photo's are the same thru-hull. Kinda stumped on this one.. appreciate any feedback.

I'm currently trying to build an order of all the replacement items and could use some guidance...

Thanks,

John

 

[Mika1]

I think it's important to keep a few things in mind:
1) A main purpose of backing plates is to distribute forces over a wider area if a seacock gets hit by something or torqued because it's hard to open/close.
2) The installations you have have lasted 20 years - they're not ideal, by a long shot, but -20 years-
3) Mainesail's work and advisements are impeccable IMO, and the gold standard for this DIY'r

That being said, *optimal* solutions aren't always practical/possible/cost effective on a production boat.

My suggestion under the galley sink would be to cut away the liner with a Dremel tool to expose an area of the hull for a properly sized backing plate and flanged adapter. Cover the cut edges of the liner with some of the ribbed plastic wire loom cover (i.e. at auto parts stores) for a clean look when finished.
Personally, I wouldn't worry about the one under the head sink because it's a smaller valve and above the waterline. You should carefully consider risks and scenarios and everything for yourself though.
To address the last pic, I might consider an asymmetrical backing plate - giving me as much load-distribution as possible (and hopefully room for a flanged adapter) without hacking up the boat any more than I have to. BTW, this would work under the head sink too, if you decide to go that route with it.
To sum up, and without taking anything away from Mainsail's top-tier advisements, keep in mind what the purpose is and get as close to the optimum as you can.