Rigging a transom mount water pickup?

After watching a video of my lower unit its the only way I am going faster. I am not really at blow out speeds and when I do get near those speeds, my entire gearcase is out of the water anyway. Pretty much just the bottom of the bullet and the skeg so the nosecone is functioning to prevent blowout. I am thinking the stock gearcase shape has less drag at cruise as well.
I would love to see some pics of how people have set up there transom mount pickups. I understand how the water hose must be routed up and loop over and down to you can still trim the engine out but how does the pump get primed if the loop in the hose is above the waters surface? I know I get some water pumped past the seal arond the water tube so maybe that would allow water to fill the pump and prime it when I launch the boat? The few threads I have found mention using a check valve which maybe hold it primed? What type/size check valve is being used in salt water?
I will be converting from a Bob LWP/Nosecone so I already have the hole in the side of the lower unit to attach the hose. Anything else I need to know or think about?
Very little info out there on this subject.
Video of my gearcase in action losing water pressure. Lower it costs me 1.5mph every 1/4".
http://www.youtube.com/watch?v=Br6JV..._order&list=UL

Transom pic. I have a small notch so I will need a 90 degree bend pickup. Might need to fabricate something as its pretty tight. I would assume it would mount on the starboard side so any drag offset torque steer?

http://img.photobucket.com/albums/v3...l/IMG_0409.jpg

This is the mount I am thinking about (one on the right). Would mounting it high with a small "ramp" ground into the trailing edge of the running surface to feed it water reduce drag? It would at least reduce the chance of it being hit by debris in the water.
I wont miss the nosecone maintenance either!

Screw it. I orderd the pickup and will post the install and results. Just not a lot of info out there on doing this. Going to run befor and after, with and without the nosecone on the lower.

If you need something custom , I can make it for you .

I'm interested how it works out too......

http://www.bobsmachine.com/Products/transom_cooling.cfm
is this the one you ordered ?

Thats the one (on the right). They gave me a Measurments and it should fit. May have to shorten the pickup a little even though its adjustable.
Thanks for the offer Tom. Let me see how things fit.

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Originally Posted by Mr. Demeanor

I understand how the water hose must be routed up and loop over and down to you can still trim the engine out but how does the pump get primed if the loop in the hose is above the waters surface? I know I get some water pumped past the seal arond the water tube so maybe that would allow water to fill the pump and prime it when I launch the boat? The few threads I have found mention using a check valve which maybe hold it primed?

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If you plumb it in on the suction side of the impeller, you don't need a check valve.

Quote:

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Originally Posted by Mr. Demeanor

What type/size check valve is being used in salt water?

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There are plastic check valves in the US. That's what I would use. Brass valves corrode stuck after a while.

For size, if you use a 1 inch clear reinforced plastic hose, you will be able to see what is going on, and you will have a water buffer in the hose.

Quote:

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I will be converting from a Bob LWP/Nosecone so I already have the hole in the side of the lower unit to attach the hose.

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Then you will be on the suction side. No check valve needed.

Here is a pic of mine, very similar mounting spot compared to yours with the notch in the transom. I have the reinforced clear plastic hose. No check valve needed, pump does pull water at an idle. Excellent and steady water pressure once going. You will need to make sure enough of the bottom edge is in the water though or water pressure will be erratic.

So...
Received my Bobs adjustable water pickup today and am not all that happy with the design. What you cant see in the pic is the square tube that slides up and down is actually held back off the transom 3/4". At speed, especially slower speeds, water will shoot up between the transom and the square tubing much like what happens with jackplates. This just creates extra drag and require the tube to be monted even higher. The length of the tube was supposed to be 4.5" and mine is 5.5" so now I have to cut it to make it fit. The hose connectors are 1/2" and mine currrently has 3/4" hose so I will need new hose connectors (may be able to use at least one of the ones I already have).
I am already modifying the mounting bracket so the adjustable square tube will be flush against the transom. No wasted water shooting up the back of the transom. It will all be captured by the pickup tube. I'll take some pics and post later.

Since theres not much info out there on this I'm just going to take pics and post as I go.

Heres what I have. I didn't like the way the pickup bracket was designed. With it holding the pickup so far back, it makes the water pressure very sensitive to trim angle. The boat runs best fairly bow high which would bury the pickup creating drag. I moved the pickup next to the transom and re-drilled the pinch bolt hole. The pinch bolt now not only pinches the bracket but its tight against the pickup tube preventing movement backward. I mounted it to a 2x4 and it it moves easily when the pinch bolt is loosened but is locked down once tightened. Adjustment should be easy. I may make the bracket two separate pieces after I get the mounting screws marked. That would make completely removing the pickup tube possible without removing the bracket from the transom.
I am going to run the boat once before I mount it to get a good baseline speed and then switch over the transom pickup.

Thanks for the info. Let us know how it turns out. I need to do something similar on my boat. I've been hesitant because there has been so little info.

I have done this on two boats. I would suggest using the lower unit water pickup along with transom mount. Do not use cheap clear hose as suggested. On the transom pickup use a check valve to so that at idle the water pump (lower unit pickup) can do its job and pump water. Run the line ( I used SS braided hose) to the midsection right below the powerhead their is a plug you can tap into. I have also run the line to the top of the block on another boat. This setup will self prime as you put the boat in the water just like you have now. I would run the line into the boat and to the engine at the pivot point with all the cables and fuel lines.

If you are not plumbing into the water pump area is there a great possibility of damaging the water pump impeller if the motor was raised a little to high. Would there be a picture of how you plumbed into the midsection?

Many thanks, Carter Powell

I am plumbing into the water pump via the existing fitting for the Bobs Nosecone and capping off the nosecone for now.