Thru-Hulls

[hcrisp]

An added bonus to removing the A4 from the boat was the chance to take the cockpit drains apart and see what was up in there. I don't know if it is true of all Bristol 27's but what I found was unacceptable and dangerous. The cockpit 1 1/2" OD male end (molded FRP) was connected to a 1" ball valve via a 1 1/2" hose, a plain steel close nipple and a plain steel connector. (This resulted in a 1 1/2" OD to fit the hose). As an added attraction the ball valve was frozen. Open.
No need to mess with hose clamps - just shook the hose and the nipple sheared at the valve.
Please don't tell me the factory did this.
Below is my solution. The 1 1/2" ID hose slides over the1 1/4" OD hose perfectly. McMaster-Carr 1" NPT to 1 1/4" barb. Don't waste your time looking for a 1" NPT to 1 1/2" barb. And the hose is cheaper.
Howard

[Hymodyne]

Raw water thru hull

Here is my solution for the raw water intake:

I found as many people adverse to an external strainer as I did in favor of one, so I found one that can be removed for cleaning. It had a bevel I did not believe I could easily make in the hull, so I blended fiberglass fibers from mat like that pictured with resin to make a base plate for the thru hull itself. the strainer opening is held in place by a circlip and can be taken out. The backing plate pictured was made with multiple layers of mat and resin, Its about 3/8 of an inch thick. Next I have to get a 3/4 NPT nipple like the one you have pictured, to route hose to my strainer.

James

[JOHN COOKSON]

When you get the new plumbing installed open and close the ball valves every so often. It will keep them from "freezing" in the open or closed position.

TRUE GRIT

[hcrisp]

Maintenance

John, I just got the boat last Fall. Haven't had her in the water yet but I will hopefully be more conscientious than the PO. There I go again, taking things personally.
Thanks, Howard

[hanleyclifford]

Howard - It is not a good idea to mix threads on a thru hull installation. The ball valve will be NPT tapered but the thru hull will be NPT straight.

[hcrisp]

Threads

Thanks, Hanley
I'll check it out soon as I get the winter cover off the boat.
Howard

[roadnsky]

...It is not a good idea to mix threads on a thru hull installation. The ball valve will be NPT tapered but the thru hull will be NPT straight.

Howard-
As Hanley pointed out the threads should be matched for the thru hull and valve.
Here's a good "How To" article to read through...

http://www.pbase.com/mainecruising/replacing_thruhulls

[ILikeRust]

Howard - It is not a good idea to mix threads on a thru hull installation. The ball valve will be NPT tapered but the thru hull will be NPT straight.

When I did mine, I went with a flange adapter, which has straight internal (female) threads, to fit the "mushroom" through-hull, and NPT male threads for the ball valve to attach to.

But I think there's a possibility that the flanged through-hull seacocks are straight threads, meant to go on the through-hull fitting. It looks to me like that's what you've got? Just double-check the threads to make sure.

[Cool Beans]

That barbed fitting is brass, and I'm assuming the red handled valve is brass as well?

From your location, I'm assuming you are sailing in fresh water, but. . .you can still get dezincification. Just an FYI. . .

Groco makes a flanged adapter base for use with ball valves. I've done 3 of the 6 thru-hulls in boat my with these. They are very nice.

Groco thru-hulls also have a composite threaded end and will allow you to use an NPT valve on the end safely. I did 2 of my thru-hulls like this. . .mostly to cap off 2 unused holes in the boat. It was cheaper and easier than glassing over them

Just tossing my 2 cents in here

[sastanley]

hcrisp, the first year I had my boat I learned all this...that pbase site of maine cruising's that Jerry posted is an authoritative source on the subject in my opinion.

I personally have been really happy with Marelon. My boat had pipe nipples glassed into the hull as thru-hulls, and I won't bother to tell you what was screwed onto them. I cut/beat/hacked them out, put in marelon thru-hulls, and then marelon seacocks. Where necessary, I cut backing plates out of PVC board of the necessary thickness (epoxied/5200'd to the hull) so the seacock would not bottom out on the threads. Then the seacock was screwed to the backing plate.

As Hanley eluded to, the issue is usually mismatched threads. Straight thread thru-hull fittings with straight thread seacocks + a thread sealer = good.

Don't forget to double clamp anything below the waterline.

[hcrisp]

NPTism

Yeah, I hear you. I shouldn't be using brass below the waterline. Zinc is a loser but freshwater is more forgiving. It beats plain steel.
The ball valve pic in #1 is tapped NPT so it fits the hose connector shown. Now I wonder about the through hull. Did someone force the NPT ball valve on the thru-hull? First thing I'll check when the cover is off.
Howard

[sastanley]

Howard...maybe...lots of times people force NPT onto straight threads and they 'get tight' so they assume they are OK, when they are really binding, but not sealing.
As I am sure you know, this is a much easier problem to deal with while the boat is dry than when it is floating..

[hanleyclifford]

Howard - While it is possible to force the ball valve down onto the straight thread thru hull, it is something you will always have to worry about. Hymodyne has the correct solution: a straight threaded thru hull with a ball valve seacock. The installation as you found it is not good. The only way to make it safe is to run a tap thru the ball valve housing to create, in effect, a straight internal thread but I don't recommend the procedure. The tap will cost more than the thru hull.

[Cool Beans]

Groco thru-hulls also have a composite threaded end and will allow you to use an NPT valve on the end safely.

Um, maybe they don't do that anymore? I bought my sets from JTD a couple years ago and the combo thread was part of the description and a selling point for me. . .I don't see them listed like that anywhere now. . .so, I dunno

[67c&ccorv]

Thru hulls - thru hull fittings - and hoses are no place to try and save money.

The Maine Cruising Forum has the best explanation of how-to install a thru hull and fittings anywhere.

I replaced 3 thru hulls - fittings - and associated hoses on my Corvette this year using the Maine Cruising forum as my blueprint - I have 3 more to go. It was a lot of hard work, sweat and money but worth it in the long run IMO.

Remember a thru hull and it's associated parts are the only thing preventing your vessel from going to the bottom.