Saturday, October 7, 2017

Nellie D. Thru-hull replacement

From Bicki Howell, Nellie D. 37VT63

We decided this year to replace all of our below the water seacocks and thru-hulls. 
The project also included the removal a legacy thru-hull which serviced a depth sounder that was no longer in use and was buried in an awkward location under our genset.  Repairing the 1-1/2 hole in the hull let from the thru-hull required grinding the exterior fiberglass to create a sloped 12" circle.  The ground area was then filled with gradually increasing circular layers (small to large) of fiberglass cloth and resin.  Approximately 24 layers were needed in total.  



Many boat owners recommend the use of a thru-hull sea strainer, especially for the engine's raw water intake.  After a lot of research and discussion, we decided not to install any sea strainers.  Last year, we experienced reduced water flow caused by zebra muscle growth in the engine's raw water sea strainer.  Even with the boat hauled we could not get adequate access behind the strainer to clear the growth.  One solution, since we were replacing the seacocks and thru-hulls anyway, was to purchase sea strainers that could be opened for cleaning (see photo below).  For us the major drawback is it requires diving over the side or hauling the boat in order to open the strainer.  Another consideration is that we have internal strainer baskets for the engine and genset raw water intakes which sufficiently screen out any unwanted debris.  Most importantly, foregoing sea strainers meant we would be able to flush or poke any blockages out of the thru-hulls while the boat was in the water.  We are happy with our decision and have cruised more than 2,000 miles without the sea strainers with no problems.  


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