Low water pickup mounting height
 

DOES ANYONE HAVE EXPERIENCE WITH WHAT THE MINIMUM DEPTH YOU CAN GET AWAY WITH ON LOW WATER PICKUPS.

I have Latham Marine low water pickups mounted on the transom near the bottom of the V on a 30ft Sutphen with twin 502s. With the front edge flush with the bottom, the back is right at 1/2" deep and they are 2 1/4" wide. That's a lot of drag and probably a lot of pressure at 75mph. Previous owners have installed a 25psi water dump regulator and they start dumping right after planned off around 25mph.

Just to reduce drag I am going to grind the back edge off a little at a time until the 25psi regulators don't dump anymore. I have water pressure gauges connected after the water pump. Anyone played with this - that could add a mph or two. I have heard that some boats have them less than 1/8" deep and round the front edges to draw up the water better.

Also, what is adequate water pressure??? I would guess 10-15psi. Thanks.

i install them even with the bottom and away from the props so the picks dont air out the water so the props slip..18 psi is a good number..

If you can put a small grove in the bottom of the boat in front of the pickup about 1/2 inch deep or so, and then start to grind and test. It will probably wind up close to leave with original bottom. An easy way to do this is put a temporary pressure gauge on the sea strainer can, and start from now when motors run cool, then make changes. 20psi is fine just remember volume cools engines not pressure, you need pressure to get the air out of the block. This is all assuming you are getting clean water.

If your PU's are in clean water, it is doubtful you are going to want 1/2" below the bottom....that may end up being a lot of grinding. Every 1/8" in WPU length will likely show on the GPS. We switched from transom mounted PU's (1/8" below the bottom) to thru the bottom PU's. Best I remember, this was worth about + 2 MPH at 90+ MPH. Originally we used a trough in front of the thru-bottom PU's but ended up filling in the trough with the PU's totally flush with the bottom. Still get 10 lbs of WP mostly from vacuum. As long as you have positive WP, IMO the amount of pressure is not important. The goal is water flow not pressure.

I was thinking of switching to these:

http://www.cpperformance.com/p-12543...ess-steel.aspx


Kinda tired of grinding away my current pickups to change the pressure.

Anyone have experience with them?

they work great,,once you have it dialed in,,weld it,or "it" will fall off at some time.

You have experience?:bsflag:

I know a guy that tore one off...

You still have to cut to fit. Had mine on and off the trail or 5 times to get it right.

I'll bite, what part of his post is bs? That is the way Reggie did mine, and if you ever get to Key West, take a walk around the pits most all of the raceboats are done that way! Why all the hostility?

14 Apache knows it all. He taught me everything I know. He is a freind of mine just joking.

Okay thanks folks. My internet been down for a couple days since I posted this so couldn't respond.
Sounds like could maybe gain a few mph since these two are so deep even though mounted flush in the front. Boat currently runs 74 with stock motors but only getting 18 degrees of timing(identical on both motors with no knock retard-but working on that issue also. I'll grind off 1/8" at a time and try it in a few weeks. Rebuilding a motor now.

How much pressure is in your can? LOL

I did some work on a 30 sutphen late this summer, the pickups were actually about an 1/8" above the bottom at the rear of the pickup. They were mounted just off center of the keel, water pressure was 10-12 lbs cruising, 15-18 wot.

+1

Thanks Lil Red, It's good to hear that at least some boats can run the scoops ABOVE flush. I will grind off a little each trip in a month or so when I get the motor back in and try it. THis first try will be only from one half inch deep to 5/16" deep. Hopefully can go much further but don't want to screw em up. Each boat can be different.

Where is the proper location of water pressure readings?
Should it be on the thermostat housing below the thermostat, or down on the block?
Is there much of a pres difference between these two locations?.