Follow up on rocky river shallow running

Scott Farris

Scott Farris

Well-known member
You all convinced me that a 25/30 hp jet was not practical for my 14-ft V-hull. So I've started to look at jack plates and prop guards. All the adjustable jack plates are rated for 350+# and V6 outboards. Sounds kind of overkill for my 103# 2-cyl / 2-stroke Nissan 25 short shaft. I did see this fixed jack plate for 150# / 35-hp and thought it might be the best bet. Does anyone have any experience with these? I'm looking to raise the outboard as high as the water intake will safely allow. (I am tentatively planing on setting the water intake at the same elevation that the shallow water drive setting does.) Ideally I hope to gain 3-4" prop height without losing significant top end speed. The prop guard (rockhopper) should help protect the parts of the prop and skeg remaining below the boat.

View attachment TH Marine JPL.jpg

So am I on a better course? Certainly cheaper at roughly $260.

Scott

View attachment TH Marine JPL.jpg
 
Another option: http://pages.prodigy.net/lee_self/index.htm

It's more for weedless running, but it will help with lift on smaller motors and might help with rocks...don't know.

Anything under 40hp, (I'm learning a bit more along here) seems you can do just fine with a fixed plate, as your motor does not need to be moved as much (if any) up or down for takeoff and running.
 
Scott,

At the time I had a long shaft 35hp on a short transom 14' deep Mirrocraft. I used that bracket and it worked well. The only thing I didn't like was that water came up between the bracket and the transom causing cold hands during the hunting season runnig a tiller. The water never came into the boat but ran over the bracket. I only had that rig one season before I traded for a boat and motor with T&T. I may not have had the bracket located properly.

My dad used one of these on his duck boat. He had a 48hp OMC that didn't have T&T and this worked great for him.

http://www.cabelas.com/cabelas/en/templates/links/link.jsp?type=product&cmCat=Related_IPL_017391&id=0013330014812a

Ed L.
 
BamaBill, interesting device, looks like it may be a bit too complicated for duck hunting and dealing with rocks. Any idea if it helps get water up to the intake or is it the same limit on how high the outboard can be raised?

Thanks,
Scott
 
Ed, Thanks for the feedback on the fixed bracket including the warning that I may have to address the water issue. I am very familiar with Tilt & Trim as I have it on my 70-hp Rude. The problem I have with T&T is that is nothing more in shallow water than a shallow water drive which is already available on the Nissan OB. In the tilted position, if I give her some gas to chug up river, the prop drives the stern deeper into the water and I'm not sure how much I really gain. With a jack plate the prop should drive the boat forward under power and not drive the transom down.

Thanks again!
Scott
 
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Scott,
order up some plate and have at it with your skill saw. Get that welder to burn your idea and see how it works.
I think you would be under the 250 and you could make another if the first one didnt work just right.
 
Bob,

The $260 is 140 for the Rock Hopper, and $88 for the fixed Jack plate and shipping for both. Of course once I see it I may decide I'd be better off simply designing a transom extension, to simply raise the motor vertically. I wont get the "cleaner" water of the set back but the shift and tilt release will be easier to reach.

Scott
 
Scott-

I have a CMC-130 on my Goliath and it's my favorite part of the boat.

I love the ability to fine tune how the boat runs in different conditions and depths. It runs VERY shallow when needed, but can go back deep for better control in rough stuff.

You might want to look into a manually movable jack plate, I know I wouldn't trade the flexibility I have w/ mine for the world.

-D
 
I've seen them with a bolt that you turn to jack up or lower the motor and I think they were made for 30 hp or so so it wasn't a real heavy thing. They did set the motor back a few inches. I think I saw them in the Cabelas Marine catalog. Wish I could remember the Manufacturer...I looked at it pretty hard thinking it would work well on my BB2.
 
I have cmc-130 hydraulic jack plates on my 1754 tunnel boat with a Yamaha 50 hp
motor.jpg


and my Bankes Crusader and Yamaha 115hp.

jackplate%20and%20steering.jpg


I love them. There might be a lighter alternative with these jackplates. I have heard good things about them. http://www.bobsmachine.com/
 
They aren't hard to make. I've seen several homemade versions that worked fine. I would think a rudimentary hand operated jacker would work well for your situation. Lots of weight though if you don't watch it.

I have another question though. I've never been able to get a straight answer from anybody. While I understand that tunnel hulls work well with props and I've seen guys go where only sleds go theoretically, I'm still not clear on whether or not they'd work well with a jet drive. It seems to me that it would work great to protect the shoe of the outdrive from rocks. They barely hang down past the hull anyway but....
 
How high you want to get the motor up? On my 14' "V", I just used a 2" X 2" hunk of treated lumber and put it on top of the transom and under the clamps on the motor. Clamps still clamped onto the aluminum transom and the motor was raised exaclty how much I needed to raise it. Like you, I needed the motor up a little and was never going to jack it up or down while running. I too did not want to tilt the motor as it drove the rear of the boat down and I run fairly shallow water.

Just a thought.

Mark W
 
Hey Scott, call me. I have plenty of 2x oak to make a test bracket. Two plys of 1.5" oak would get you back 3".


farris.jpg

 
Just went to Cabelas website and they have about 5 manual jack plate set ups. My biggest wory would be betting water to the intakes if the motor is raised enough to miss rocks and prop cavitation causing over revving.
 
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They aren't hard to make. I've seen several homemade versions that worked fine. I would think a rudimentary hand operated jacker would work well for your situation. Lots of weight though if you don't watch it.

I have another question though. I've never been able to get a straight answer from anybody. While I understand that tunnel hulls work well with props and I've seen guys go where only sleds go theoretically, I'm still not clear on whether or not they'd work well with a jet drive. It seems to me that it would work great to protect the shoe of the outdrive from rocks. They barely hang down past the hull anyway but....
Click to expand...


Jay, some jet guys think that the tunnel generates too much entrained air in the water which messes with the compression in the impellar. To counter this some tunnel hull users install a vent using PVC or metal piping and a ball valve. They open the valve when on step to "let the air out". If you come off step in "deep" water and forget about the valve they take on water. The modern method is to pipe the valve all the way back to the stern so that the water never enters the hull. This just gives you more stuff to hang up on in the back of the boat.

In shallow water the tunnel boats work great with jets and keep the amount of gravel being sucked up to a minimum.

Here in AK there is more of a concern about the depth/height of the tunnel than the use of a jet vs prop. The older Roughneck tunnel boats had a tunnel over 3 inches tall, which caught and edge on high speed turns causing some boats to flip. Proof of this I do not have but that is what the dealer told us during a show a few years ago.
 
Scott,

regarding the rockhopper. you will lose some top end speed. i'm no longer able to get on plane with 2 people in my boat with the hopper. before the rockhopper, it would take some time to get on plane with a passenger, but most of the time it would plane. my aluminum prop has still taken a beating just from loose debris and shells, so i'll be switching to stainless. i'm hoping the stainless prop will add more power with the hopper. also, the wing on the hopper doesn't add any lift, it just helps prevent sticking the prop in soft mud. the nose of the hopper works great at collecting hydrilla and it slides right off when you raise the motor. it doesn't keep all the weeds out of the prop, you just don't have to clean it as often. it also helps protect the front of the lower unit.

regarding low water pickup. check out bobsmachine.com i spoke to them several years ago when i was trying to set up my tunnel hull to run shallower. they have transom-mounted pick-ups that might work for you. also, i believe they can add a low water pick-up to your lower unit instead of the transom pickup. i'm not sure either would work for you or be within your price range, but you it's worth a call. I didn't buy either.

good luck

Larry
 
Thanks for the follow up Ray. It makes perfectly good sense. I wondered if the "bubbles" would be the issue.

Happy New Year!
 
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