Thru hulls

[ghebbns]

Hi all,

I am replacing the three thru hulls located under the sink in the head. Two are 1/2 inch and one is 3/4.  I have read Mainesails excellent article and want to do this properly.

I have 3 bronze seacock with flanges but they are all 3/4 inch.  Is there any reason not to drilll the hole in the boat larger and use 3/4 thru hulls for the engine and head intake? If i do so, what is the best way to connect the 1/2 inch hoses to the 3/4 seacock?

Thanks

Greg

[Jim Hardesty]

Greg,
Get some thing like this in bronze.  The link is for brass not a great choice.  Plastic may be OK.

http://www.discounthydraulichose.com/product_p/102-xx.htm

Jim

[Ted Pounds]

DO NOT use brass, ever.  The only "plastic" that is acceptable is Marelon which is glass reinforced nylon.  I would stick with the same size thru-hulls to make it simple and not have to worry about adapting to the hoses, but that's just me...

[Dave Spencer]

Greg,
I don't see anything wrong with increasing the size of the through hulls and adapting down as Jim suggested; especially if you already have some good flanged bronze 3/4" seacocks which are expensive.  I followed Mainesail's directions when I replaced all of the through hulls on my previous boat - a 1978 CS27 that was fitted with (gulp) gate valves.  It was lots of work but things went well. 
Be careful with the through hull fittings though.  I was considering replacing the OEM Marelon through hulls on my C34 with new ones; preferably bronze.  But the flush flange on the through hull has a huge outside diameter and I couldn't find any new through hull fittings that would match so I left them alone.  The pictures below show the through hulls under the head sink.  I had scraped away a little of the fairing material around the fitting when I took these pictures.

Good luck with your refit.  Keep us up to date with pictures!