Seawater Pickup

[76SeaRay]

When I test fitted my engine a few days ago, I found that I need to notch out a section of the stringer where the starter and flywheel housing locate. I realize now that I need to determine where and how to mount the seawater pickup for the pump before I finish close the stringers and floor in the engine bay.

It appears my choices are through hull or through transom. I am not excited about holes in the bottom of the hull so was wondering if that is the preferred method of pickup? If I install a through hull pickup, where do they typically get located? Anybody have pictures of an install with Alpha Drive and 5.7l engine?

If I use a through transom, I have about a foot and a half space between the gimbal housing edge and the inside edge of the trim tab. So, I am guessing I would install it midway in that space between the two on the starboard side. Does that sound like it might work? If using a through transom, is a seacock needed to shut off the pickup at the dock? I have my Garmin Echo Map transducer that will have to be mounted in the similar space on the port side of the transom.

 

[flashback]

Why not use the pump in the alpha?

 

[76SeaRay]

I will use both on a Y adapter. This is a full closed system with dry joint exhaust.

 

[dingbat]

Transom pickups sux. Priming issues….

I have scoop type, thru hull pickups on my bait and washdown pumps. No problems priming. Have water flow thru bait well w/o pump running if anchored (tidal flow)

It’s your boat, but anything below the water should have a seacock just in case

Perko 9-0065dp4plb

Max. Pipe Size: 1/2" Max. Hull Thickness: 2-1/4" Dimensions Strainer: 3" x 4" Cast Bronze Machine Slots

www.iboats.com

 

[kenny nunez]

Do not be afraid to go through the bottom with a valve. The one advantage is one less “rooster comb” behind the hull. The “Y” connection is a definite good move to keep the drive cool and also works with a flush out .
Greco # TH 1000 Through hull 1” NPT pick up
Groco # IBV 1000 valve
The rest you will have to provide to plumb the system together.
These are some of the pieces I rigged my Donzi with.

 

[76SeaRay]

So, if I go with thru hull, what are the pro's and con's of those two types of fittings, Perko scoop versus Greco flush mount?

 

[kenny nunez]

It does not matter If you do not mind the extra “Rooster Comb”. They are all suitable for the job.
They can also be mounted through and on the underside of the trim plane. I had a 24’ Campbell once that was set up that way.

 

[76SeaRay]

Actually, I was wondering about which was better the thru hull scoop type or the thru hull flush mount....

 

[kenny nunez]

I would only use the scoop style, it has a grill that will keep out debris.

 

[76SeaRay]

Well, I like the looks of the triangle base valve but using the scoop means you can't really use the triangle base valve since both the scoop and the triangle valve both have to be oriented to specific direction. No way to really tighten it. I see that using a 3/4 inch valve was mentioned. The hose to the seawater pump is 1 1/4 inch so should the valve and fittings be 1 1/4 inch also? ID versus OD callouts on parts gets a bit confusing at times.

 

[kenny nunez]

1” NPT pipe is plenty enough water supply. 1/14” I.D. hose will fit over it.
Consider that in the drive there is a much smaller pipe which will deliver enough water for a sea water cooled 5.7 But as we know will not cool a fresh water cooled V style engine.

 

[76SeaRay]

Great, thanks. Now I have to figure out whether I can find a way to install a thru hull fitting... The only thing I can come up with for mounting it is shown by the arrow in the picture. It would need to be boxed in and a hatch in the floor over it for access. I have to put the engine battery on that side (starboard) along with the tilt/trim pump assembly so limited space. The other side (port) has the house battery and the trim tab pump so limited on that side too.

 

[kenny nunez]

If you are going through the bottom of the boat you can also mount the through hull fitting in front of the engine. Just be sure the trailer boards will not interfere.

 

[76SeaRay]

Not sure I have room there either.

 

[Bondo]

Ayuh,.... Whatever pickup you decide on,.....
Make sure you can feed it with a hose, for outa the water work,....

 

[76SeaRay]

I am planning to put in a Y so that the Alpha pump feeds into the seawater pump in addition to the through hull. I could shutoff the through hull and then feed water from muffs to the heat exchanger through the seawater pump for work running on the trailer (assuming that would be sufficient flow without load on the engine).

 

[76SeaRay]

Does anybody have a link to (or a part number for) a bronze or stainless steel Y fitting that works with the 1 1/4 inch seawater hose and the 3/4 inch drive pump hose to feed the drive pump outlet hose to the seawater inlet hose?

 

[kenny nunez]

If there is a Home Depot/ Lowes in your area they will have everything that you need in bronze. The clear hose with the cord inside is good enough.
That is where I found what I needed for my Donzi for the final connections.

 

[flashback]

https://www.boats.net/product/mercury/862993

This may work for you.

 

[76SeaRay]

Well, back to my fit problems for a thru hull fitting. I think I have a bigger issue under the hull as opposed to finding a spot in the engine bay. I only have 5 inches space between the center of the keel and the edge of the first trailer roller. The trailer rollers cover the whole area where a thru hull would go. I only have 6 inches from the back of the transom to the row of rollers.