Topic: Relocation of Cockpit Drain Through-Hull Fittings

In this image I came up with an alternate solution.

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Re: Relocation of Cockpit Drain Through-Hull Fittings

So here is the explanation:

As shown in a previous post when I tried to install traditional seacocks in this area they interfered with one another.  Therefore I had to chose between moving the holes or finding another solution. 

My existing through hull fittings sit flush to the hull surface and the fibreglass in this area has been recessed accordingly.  This makes a fibreglass bubble inside the boat about 4" in diameter and as thick as the hull in this area -- about 3/8".  Relocating the holes was going to be a BIG hassle and I feared doing more harm than good.

Groco makes a Flange plate which looks like the triangular bottom of a traditional seacock and has the standard straight thread.  The top threads on the plate are NPT (tapered thread) so that standard ball valves and other fittings may be employed.  IT IS NOT IDEAL but it is a solution for situations such as this. 

I played with 90 degree elbows (as depicted) and 45 degree elbows.  I also considered using elbows both above and below the valves so that they could be mounted vertically.  These are in at about 45 degrees to the waterline.  If you try this route bite the bullet and buy the extra fittings do play around with this.  Your boat may be different from mine and you may be able to work out a better arrangement for your boat. 

Also note the location of the handles of the valves -- they are long and any installation must take their positioning into account.  You need to be able to have the valves both fully open and fully closed without interference.  Ideally you also need to plan for a persuader of some kind.  These ball valves are very stiff to turn.  I have not yet worked out what to do with the engine control cables shown in the picture but I expect I will be moving them around a bit.

Yes I made huge backing plates.  This was for several reasons.  The original installation did not use valves and hence did not have the weight and loads associated with them.  Then new valves and fittings are very heavy and are very stiff to turn -- I wanted to be certain that I would not be tearing apart the boat if I had to use a lot of force.  I can stand on these if a situation (very unlikely) arises where I need to do so.  Also note the curvature in the hull in this area.  These plates were originally 2" thick and I machined out the centres to less than half that for the boat's curvature.  Because the fibreglass in the are of the actually through hull fittings is recessed into the boat I also had to carve circular indentations into the undersides of these plates.  They are a bit less than 3/4" at their centres.   There was a lot of grinding and fitting and grinding and fitting.

The plates are coated in epoxy and everything has been bedded with 4200.  I used about a tube on this job. 

The original install did not have the three anchoring bolts.  These are silicon bronze and were easy enough to source out of New Jersey but were extremely costly to ship to me in Montreal.  It worked out at about $10 a bolt but it is a proper install.  I read somewhere that stainless and bronze were not galvanically compatible.  (Of course my boat lives in fresh water...)

Outside the boat I had to drill and countersink for these anchoring bolts as well as touch up the Interprotect bottom paint in the area.  Some boltheads lie flush to the hull, but the lower bolts are in at an angle.  This is because of the hull curvature.  I'll jam a little butyl or 4200 in to level the holes in the spring before applying antifouling paint.

You will also note the close proximity of my engine coupling to these valves.  The port side is so close that I could not spin the 90 degree elbows onto the flanges.  Therefore I assembled these fittings on a vice to get them tight, and installed them in the boat as complete assembles.  Installation is a two person job but it goes quickly (especially after days of prep work).


Hindsight -- The original boat had a perfectly good installation for the cockpit drains.  The weak links in these assembles are the hoses.  Annual maintenance should take care of this with ease and give good piece of mind.  For interest, when I shared my tale of this project with a surveyor he said that ball valves were recommended but not required.  I could have used gate valves or left well enough alone and had no valves at all.  Since my boat lives in fresh water gate valves work just fine and would have solved a lot of installation headaches.


If you have questions or comments fire away.  I am happy to share what I have learned here. 

Christopher

Re: Relocation of Cockpit Drain Through-Hull Fittings

thats a proper installation, and Construction Standards for Small Vessels (2010) - TP 1332 El standards do call for:

3.3.1.2 Means shall be provided for positively shutting off underwater penetrations, with the exception of wet exhaust systems.

so

only thing that raises a flag is the hose...  i'd think about ditching the vinyl hose and replacing with wire reinforced exhaust hose

Re: Relocation of Cockpit Drain Through-Hull Fittings

That is a fair comment.  Having worked with the heavy exhaust hose I would be reluctant to try it here.  It took heat and a lot of effort to mangle these short lengths of hose onto the barbs.  I destroyed a length in the process.  I do not believe that I could torture the exhaust hoses in the same way.  If I HAD to use the heavier hoses I would be repositioning the valves and adding elbows for longer pipe runs.  In my specific case, when I tried this the pipe runs were almost horizontal and I saw little benefit in adding more turns and resistance to the system.

I will just have to inspect these clear hoses regularly.

Thanks for the compliment Stefan!

Re: Relocation of Cockpit Drain Through-Hull Fittings

Oh -- one other sharing.  This job is costly in materials and is a huge time vortex.  I had not planned to do it at all this year and circumstances forced me into it.  Ordering all the various bits and scheduling the work took so much time my poor boat spent the season high and dry.  sad

6 (edited by stefan_d 2014-10-11 09:20:34)

Re: Relocation of Cockpit Drain Through-Hull Fittings

again just differences in these boats and how they made them.  beautiful job and you will be able to sleep at night without worrying that she might sink (both while on the boat and during the week when she's alone in the marina....)  some of the stuff out there is downright scary (grey pvc fittings, gate valves so green and seized, etc etc)

on my 74 the drains are at the far aft end of the cockpit, and are just 3/4" dia.  so it was a little easier to put everything together. 

most important thing is to actually take the the time to pull the floor panels at the start and end of each season, and exercise those valves....  means a chance for a good look (and clean) at the engine compartment and all the things that look sooooo far back from the companionway steps.....

Re: Relocation of Cockpit Drain Through-Hull Fittings

Just a further note. On my boat the drain pipes are crossed which prevents (or lessens) any water from back flowing into the cockpit when heeled over.
John

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Re: Relocation of Cockpit Drain Through-Hull Fittings

On my boat - no. 156, laid up in October 1975 - there were no stopcocks on the cockpit drains at all. The boat would have sunk in about five minutes if the hoses had ever come off!  In fact, most of the stopcocks in the boat were cheap plumbing fixtures.

Can't imagine why they didn't install proper stopcocks at the factory when they were building the boat.

PS: Guess the first job I did when I bought the boat -- I put in brand-new stopcocks all around, including the cockpit drains.

PPS: And the bilge pump rubber had perished! Guess the second job I did when I bought the boat!