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post #1 of Old 03-25-2011 Thread Starter
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Thru-hulls

I have 1976 Gulfstar 43 center cockpit ketch. It has twelve below the waterline thru-hulls. A number of them are no longer in use. These I plan on having glassed over later this year when I have my hull blasted and new barrier coat applied. Some of the other thru-hulls I plan on installing new above the waterline and then glassing over the old ones. Here is a list of my existing thru-hulls.

1) Forward head toilet discharge
2) Forward head sink discharge/toilet intake
3) Galley sink discharge
4) Refrigeration intake
5) Refrigeration discharge
6) Bilge pump discharge
7) Cockpit drain
8) Raw water intake
9) Speed Log
10) Depth transducer
11) Aft head toilet discharge
12) Aft head sink discharge/toilet intake

Bilge pump
This week Iím planning installing a new bilge pump. The existing pump is not automatic and is wired thru a breaker. The thru-hull is below the waterline, is only Ĺ dia, and it has a home depot type brass ballcock . My plan is to install a new thru-hull above the waterline, new hose and new bilge pump wired directly to the battery with the test lead to the breaker panel. My question on this is, if I install the new thru-hull two feet above the waterline should I still install it with a seacock ?

Forward head
The toilet in the forward head was removed by the previous owner. I plan on removing the sink and turning the area into a shower. Glassing over both of the thru-hulls, #1 & #2. Install a shower sump pump that discharges thru a new thru-hull above the waterline. Looping the hose from the sump to the ceiling and back down to the new thru-hull.

Refrigeration
The unit is probably original equipment and doesnít work. When I replace it, it will be an air cooled unit. So I donít see a need for these thru-hulls. I plan on having them glassed over.

Speed Log
The speed log doesnít work. Do I really need one? Iím thinking about removing it and glassing over and just using relying on the GPS.
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post #2 of Old 03-25-2011
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If you have a wind machine (anemometer) the log may be coupled to provide actual vs apparent wind. If you don't have such a setup or you don't clear your paddle wheel often enough, it may not matter, just so long as you realize the GPS will give you speed over the ground--not speed through the water (unless there is no current).
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post #3 of Old 03-26-2011
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New bilge pump outlet. If the outlet is 2' awl I wouldn't bother with a seacock PROVIDED there is an anti syphon loop fitted to a high loop in the outlet run of the pump.

However if your boat is 'coded' for charter it may be a requirement to have all hull breaches closable.

Speed log. GPS gives speed over the ground not through the water. If you are in tidal or current conditions you are not reading boat speed at all. Wind speed really doesn't relate to water speed.

Last edited by nimbusgb; 03-26-2011 at 04:23 AM.
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post #4 of Old 03-26-2011
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1) Forward head toilet discharge
2) Forward head sink discharge/toilet intake
3) Galley sink discharge
4) Refrigeration intake
5) Refrigeration discharge
6) Bilge pump discharge
7) Cockpit drain
8) Raw water intake
9) Speed Log
10) Depth transducer
11) Aft head toilet discharge
12) Aft head sink discharge/toilet intake

From the above list, I'm confident that several of these could be combined using "Y" valves, and at least two could be eliminated completely.

The speed log is just about useless. The only speed that really counts is your speed over ground, which is the information derived from your GPS. Glass that one over.

The depth transducer is another that you may be able to eliminate. This, of course, depends upon whether your boat's bottom is cored or solid glass. If the bottom is solid glass, which is the case with most boats, you can shoot the depth directly through the hull from the inside using a puck type transducer. If the bottom is cored, then you'll have to stick with the thru-hull transducer.

Good Luck,

Gary
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post #5 of Old 03-26-2011
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For gray water drainage, I would want the thru-hulls at the waterline or below, but not above. Gross staining down the hull, otherwise.

The bilge is an exception. If exiting the side, it is nice if it will remain above the waterline when heeled in that direction. I would probably install a seacock out of an abundance of caution, but I suspect you will never close it, ever.

Another option to glassing them over may be to replace the hardware and safety wire the seacocks closed.

By speed log, do you mean the paddle wheel speed transducer? On a 43 foot boat, that it going to be very helpful. As stated GPS is only speed over ground. You need speed through the water to help detect sail trim or engine/prop issues.


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post #6 of Old 03-26-2011 Thread Starter
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I like your idea of a in-hull transducer and glassing over the old. My hull is solid glass, I've been told its 1-1/2" thick.
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post #7 of Old 03-26-2011 Thread Starter
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The boats seacocks are the old Groco series 200 that have the tee-handle and rubber plug. Most of them are in "OK" condition. But I think they're at the end of their serviceable life. If I could buy new or rebuilt ones I would, but you can't get them anymore. So my plan is to eliminate one I don't need, and install new for the rest. New thru-hulls, backing plates and seacocks.
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post #8 of Old 03-26-2011
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Quote:
Originally Posted by ctj1950 View Post
I like your idea of a in-hull transducer and glassing over the old. My hull is solid glass, I've been told its 1-1/2" thick.
You can check this out fairly easily by placing a water-filled baggie on the hull, then placing the transducer on the baggie. It should read the depth if the hull is solid glass. Keep in mind that it will have to be on either side of the keel, though. It cannot read through the keel.

Good Luck,

Gary
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post #9 of Old 04-04-2011
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Am in the process as well of redoing my bilge pump configuration. Useing two pumps one 500 to a 1/2 in thru hull and a 3000 to a 11/2 thru hull. I'm not to concerned with the 1/2 inch thru hull as it will be placed below the rub Rail I'll use a vented loop to prevent back flow. But where do I run the high capacity pump to ? There is a thru hull in the transom but the run from the High Capacity pump to the Transom is over 5ft and involves some odd bends and corners. Is it safe to put 11/2 in thru hull below the the rubrail. I'm concerned with backflow whilest heeling even with a vented loop in the line. As usual a tradeoff is required. Any good advice is appreciated.
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