low water pick up

[dombern34]

last year I purchased a tunnel hull boat to fish the shoals here on the local river as well as the flats. well this particular boat is a 1860 triton redfish series and it is equipped with a mercury 90 opti. these motors didn't come with low water pick up. so when running up the river the jack plate would be down and my water pressure would be around 9-10 PSI. getting to the shoals I would jack the motor up and back off the throttle a little but on any sort of turn that makes the water drop out, my motor would start sucking air and my alarm would sound on my motor which shut it down to a safe rpm, which in turn cause me to bounce off a few rocks every time. useless to me if I can't run the motor up.

searched around for a fix. I figured I would bite the bullet and put a low water pick up on my foot from bobs machine shop. it would run me about 650 plus 150 in round trip shipping.

was on facebook one day and seen a guy named Mike Waston. he's from Tenn and is a tunnel hull specialist. I called him up and after talking to him for a while, he mention all I needed was to close off the top 4 holes of my intake and add scoots and I would never have this problem again. its kinda like a straw. if you have a have a hole in your straw above your level of drink, you'll never get it up the straw. just like on my motor, once that very fist intake hole broke the service. I lost all water pressure.


so I sent my foot off to him on a Monday. he welded up my top four holes and welded on my scoots. repainted my foot and sent it back. his service was 200 bucks.... I had my foot back the next Tuesday.


I bought a four blade prop while my motor was sent off because the boat was running the wrong prop for what I was looking for. I got everything back together and was able to put it in the water yesterday.

my water pressure is now 18-20 psi I can run wide open with the jack plate all the way up and even turn the boat as hard as I want with only dropping down to 12psi.

if anyone is running a tunnel and you're having this kind of issue I would HIGHLY recommend talking to Mike Waston. he's a great guy who will help you out.

[Flint River Pirate]

Interesting, thanks for sharing.

[RiverRunner]

Yes, thanks for sharing! I'm very interested....

[Gulf Coast]

Some food for thought....friend has low water p/u on his boat....says at idle sometimes it runs hot, picks up too much mud/shoal

[dombern34]

haven't had any problem idling yet. even in reverse like to back off a trailer or a bank after I've beached it, the pressure hasn't gone below 6-7 psi. I know on my last motor, which was a hpdi 250 with the lower water pick up. I had a lot of issues with it being clogged. I never seen over 12 psi on that motor even at 65+

[Gulf Coast]

May be a Yamaha problem....his is a 200 HPDI

[silverking]

You may have already done this, but check with your dealer. A modification of this type could void the engine warranty if it's still under coverage. The benefits may outweigh the risks, though.

[dombern34]

I'm sure it does, but my motor is out of warranty anyways. I would think making any changes to the intake system permanently would void the warranty.