Cooling water thru hull pickup placement

[Bob Rosa]

The hull I am trying to complete is ready for a cooling water pickup. I need to learn what are the best design practices for placement of the hole for this pickup and the orientation of the pickup. I want to use the cast brass clam shell style and my hull design has a 1.75 inch step 15 feet from the bow. 25 foot OAL. My trailer bunks are 2 foot either side of the keel, so lots of clearance there.

 

[bajansailor]

Bob, do you have any photos that you can post showing the hull please?
I think that a photo or two would help a lot re folk on here offering suggestions re placement of the intake.

Edit - excellent photos, thank you!

 

[jehardiman]

Bob, you will want the cooling water pickup well aft near centerline. The idea is to place the pickup in an area of high pressure, usually with the opening facing forward to help the raw water pump.

 

[Bob Rosa]

Thank You! What do you think of about 8 to 12 inches in front of the step?

 

[C. Dog]

Bob you have a well engineered work of art there, congratulations.

The other possibility is a transom mounted raw water pickup. These can purchased or easily fabricated and avoid having the skin fitting below the water line.

Downside is I haven't seen a bronze one in a long time, stainless mostly; and you have a metal lump on your transom, which matters little on most boats with numerous items there already, and maybe wouldn't be so bad on your boat if you are mounting a duck board out the back, and paint the fitting.

 

[C. Dog]

Bob something else I overlooked, the inlet is on suction so will need appropriate hosing so that it doesn't collapse and cook your engine, and that stuff should not (and cannot) do tight radii.

When considering placement the limitations of the hosing are an important consideration. It does need some light bends to help it absorb engine movement.

On the style of pickup, I find this type the best.

https://cimg9.ibsrv.net/gimg/www.th..._a9b3848c44df2ef846f55ad7843014eb80ca520b.png

 

[Bob Rosa]

Bob something else I overlooked, the inlet is on suction so will need appropriate hosing so that it doesn't collapse and cook your engine, and that stuff should not (and cannot) do tight radii.

When considering placement the limitations of the hosing are an important consideration. It does need some light bends to help it absorb engine movement.

On the style of pickup, I find this type the best.

https://cimg9.ibsrv.net/gimg/www.th..._a9b3848c44df2ef846f55ad7843014eb80ca520b.png

Thank You! The pickup is exactly what I have. Two actually I have. A 1.00 inch and a 1.5 inch. Not sure which one I'll use.

 

[Bob Rosa]

Bob something else I overlooked, the inlet is on suction so will need appropriate hosing so that it doesn't collapse and cook your engine, and that stuff should not (and cannot) do tight radii.

When considering placement the limitations of the hosing are an important consideration. It does need some light bends to help it absorb engine movement.

On the style of pickup, I find this type the best.

https://cimg9.ibsrv.net/gimg/www.th..._a9b3848c44df2ef846f55ad7843014eb80ca520b.png

Thank you! The transom mount would put the pickup 14 feet from the crankshaft mounted pump.