Replacing the engine cooling water intake seacock - two questions...

Kukri

Kukri

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Boat is an Ohlson 38 and we are replacing a very knackered BMC 1.5 with a reconditioned one.

The old inlet started with a "through hull which had a gate valve on it which came apart in my hands guv... which was in turn threaded onto the usual type of bronze tube filter. I dislike these since Pete Thomas suffered the sinking of Transcur at Pin Mill...

Having bought a respectable Blakes' seacock ...I have had forty six years of wooden boats and I am nervous about fitting a new seacock in the place of a "skin fitting" in a GRP hull. If the external diameter of the Blakes is less than that of the old skin fitting - what do I do? Epoxy? Sikaflex? I'll replace the backing pad with a new bit of cross laminated teak on first principles of course.

I think I want a Vetus big plastic filte,r but my recollection of the one I fitted in the ex boat is that one has to be very careful to locate this more or less on the waterline or a little below it. Or is there a better fitting now?
 
Minn said:
Boat is an Ohlson 38 and we are replacing a very knackered BMC 1.5 with a reconditioned one.

The old inlet started with a "through hull which had a gate valve on it which came apart in my hands guv... which was in turn threaded onto the usual type of bronze tube filter. I dislike these since Pete Thomas suffered the sinking of Transcur at Pin Mill...

Having bought a respectable Blakes' seacock ...I have had forty six years of wooden boats and I am nervous about fitting a new seacock in the place of a "skin fitting" in a GRP hull. If the external diameter of the Blakes is less than that of the old skin fitting - what do I do? Epoxy? Sikaflex? I'll replace the backing pad with a new bit of cross laminated teak on first principles of course.

I think I want a Vetus big plastic filte,r but my recollection of the one I fitted in the ex boat is that one has to be very careful to locate this more or less on the waterline or a little below it. Or is there a better fitting now?
Click to expand...

Pete`s broke as i understand it by a tool box falling onto it, hardly an every day occurrence
 
Minn said:
Yes; that's what the instructions say, but if you follow those instructions and at any time the top seal ("O" ring) is not perfect, it will suck air in, the cooling water supply will fail and you will cook your engine. Don't ask me how I know that!
Click to expand...
Did it fail suddenly? I can see that it can be difficult to get a good seal when refitting the lid, applying silicon grease helps with installation and sealing.
installed below waterline with a leak would fill the boat with water?-
 
Minn said:
Boat is an Ohlson 38 and we are replacing a very knackered BMC 1.5 with a reconditioned one.

The old inlet started with a "through hull which had a gate valve on it which came apart in my hands guv... which was in turn threaded onto the usual type of bronze tube filter. I dislike these since Pete Thomas suffered the sinking of Transcur at Pin Mill...

Having bought a respectable Blakes' seacock ...I have had forty six years of wooden boats and I am nervous about fitting a new seacock in the place of a "skin fitting" in a GRP hull. If the external diameter of the Blakes is less than that of the old skin fitting - what do I do? Epoxy? Sikaflex? I'll replace the backing pad with a new bit of cross laminated teak on first principles of course.

I think I want a Vetus big plastic filte,r but my recollection of the one I fitted in the ex boat is that one has to be very careful to locate this more or less on the waterline or a little below it. Or is there a better fitting now?
Click to expand...

You could consider selling the Blakes seacock and fitting a Trudesign ball valve with a load bearing collar


370b9bacca539420c8a2864d7dc7b720-full.png

http://www.trudesignplastics.com/marine/products

.
 
If the brakes is smaller than the existing through hull fitting, plug the old hole as per West Systems directions and re-drill for the Blakes elsewhere.

+1 for the Vetus strainer above the waterline. If you mount it below, you can't take the cage out for cleaning without letting water into the boat and how would you plug the leak if the case split (as my old Volvo one did).

I've no experience of the Truedesign ones but I do like the concept.
 
My inlets are forty years old. Presumably gunmetal bronze skin fitting, then a gate valve which is new, then the bronze standpipe strainer with removable top. It blocks regularly, some days I have to do it more than once due to weed in the harbour, I don't see the problem, take the top off, pull the strainer, open the valve to flush through, sometimes I have to rod it though, alkathene with serrated end nearly as big as the hole is good.

https://www.asap-supplies.com/fitti...raw-water-intake-strainer-hull-mounted-402073

Edit: someone had the bright idea to fit the strainer away from the inlet, after a 90deg bend, and that was approved by the Seafish construction and use surveyor.
 
I have the same sort of thing that fisherman has shown, fitted remotely in the engine bay, with the static waterline about half way up. They are tricky to mount because they have no lugs, I used a backing pad of wood and large jubilee clips.
As intimated, you have to figure out how to rod the remote pipe if it should be blocked, mine has been ok.
Fill out the old ole with mat and resin, unless the difference is huge I can't see it making any difference to the strength of the finished piece
 
Blakes seacock is not ideal for an intake. You need first to check that your engine only needs 3/4" - some need 1". The accepted way to install now is to use a ball valve (DZR, Bronze.or plastic if you don't fancy metal) and fit the Vetus strainer directly above it above the waterline. You can then see water flowing, clean the strainer without shutting off the water and rod straight down through the seacock. Very reliable if you make sure all the clips are tight and the top O ring sealed properly. If it is not you will see bubbles in the water.
 
Tranona said:
Blakes seacock is not ideal for an intake. You need first to check that your engine only needs 3/4" - some need 1". The accepted way to install now is to use a ball valve (DZR, Bronze.or plastic if you don't fancy metal) and fit the Vetus strainer directly above it above the waterline. You can then see water flowing, clean the strainer without shutting off the water and rod straight down through the seacock. Very reliable if you make sure all the clips are tight and the top O ring sealed properly. If it is not you will see bubbles in the water.
Click to expand...

Thank you.
 
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