Replacing in-line valves with seacocks

Two of the five thru-hulls on Freya had been re-plumbed with in-line ball valves by previous owners (the factory installation relied on Spartan bronze seacocks everywhere). As noted by Maine Sail in this excellent article, using in-line valves on thru-hulls is usually not a great idea, mostly for two reasons: 1) the threads are often incompatible (NPS on thru-hulls, NPT on valves), resulting in a very poor fit (three or four threads at most); 2) compounding the previous issue, the lack of a flange on in-line valves means that nothing prevents them from twisting (and eventually disconnecting from the thru-hull) when turning the handle.

The above would have been good enough reasons to replace the valves but in Freya‘s case, there was another: at least one of the two valves was made of cheap brass. The risk of de-zincification, coupled with the issues inherent to in-line valves, made me wary enough to schedule a quick haul-out to replace both. There was a spare, new Spartan bronze seacock identical to those used at the factory stored in one of the boat’s lockers (evidence that another owner was aware of the problem?) – I decided to use it for the engine intake. For the head, I went with a newer model from Groco (BV-750), also made of bronze.

I worked in tandem with one of Svenden’s employees to replace both valves in about 4 hours. The process was reasonably smooth: removal of the old thru-hulls, dry-fitting of new thru-hulls and seacocks, cutting of the thru-hulls to size, drilling of additional holes for the flange bolts in the head, final assembly using copious amounts of 3M 4200 fast-cure to seal everything. The pictures below document most of the process. You’ll be able to see how thick the hull is in these areas, and also how it is further reinforced with glassed-in backing plates (meaning I did not have  to install any, a significant time saver). Yet more evidence that Cape Dory knew how to build quality boats.