Just another Moderator
Join Date: Sep 2005
Location: New Westminster, BC
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Since you seem to know you have a bottom-growth problem that's the most likely cause now.. does your sink drain? You mention the cockpit won't drain, but if the blockage is below the sink drain tie-in then the sink won't drain either..
Straight through tubes are not ideal, as mentioned above.. I wonder if that was factory or if someone 'improved' things... One of your first chores on haulout should attend to these, after reading our MaineSail's excellent article on installing proper through hull valves.
1984 Fast/Nicholson 345 "FastForward"
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)