Jack Plate question

[Redbelly]

If I were to put a HJP on lets say a 50hp motor on a 16' aluminum boat, say a G3. How much shallower can the motor run with a 6" set back plate with out a tunnel?


Would adding a 4 blade prop and a Bob's cav plate increase the capability?

[silverking]

Six inch setback is probably going to offset the center of gravity on a boat that size and cause stern squat. The cavitation plate will help some but not all that much. Four-blade prop may or may not make much difference in performance. Depends on the pitch, cup, engine mounting height, pick-up ports and other factors.

Saw your similar post on another site. Why do you want to run so shallow? Still won't help if you find a rock a half-inch higher than the skeg (and there are hundreds out there) and by running super shallow you are running over the exact fish you want to target. Go slower to work into the general vicinity, then use the trolling motor and/or push pole to get close. That way you won't disturb the fish or disrupt patterns and have a better chance of catching them.

[Redbelly]

Silverking you ask why do I want to run so shallow? You answered the question.


Things in the water from the lighthouse to Rock Island. Fast falling tides, shallow areas in front of creeks, and those instant oyster bars!

After clunking the bottom and chunking the skeg on my previous flats boat enough I decided to change. My fishing style for inshore has changed.

I once had a Scandy White tunnel that would scare you it would run so shallow! I'm not out to race across the shallows, but travel closer to the shoreline and have decent speed to get where I'm going.

[silverking]

Understand wanting to increase access to certain areas. It's the reason why I bought my Beavertail. But there is a big difference between floating shallow and avoiding hazards and running shallow.

Seeing too many boaters running anywhere and everywhere without consideration that those practices are definitely changing fish patterns and harming the environment. The number of prop scars across the grass flats is more evidence of careless operation.

By the way, in most cases a standard modified V-hull will float shallower than a tunnel because of water displacement.

Good luck with your boat search/modifications.

[Salty Gator]

I have a 22’ pathfinder with a pocket hull and a jackplate. I can’t really run with my jack plate higher then a couple of inches without it cavitating. If I installed it to run shallower, I’d be extremely disappointed. I really only use it when idling in really shallow water. I know on some boats, you can really jack it up and still run, but not on all boats. Good luck

[STMU]

If I were to put a HJP on lets say a 50hp motor on a 16' aluminum boat, say a G3. How much shallower can the motor run with a 6" set back plate without a tunnel?

I have a 16' aluminum tunnel hull and I thought about the same thing. I went through the pros and cons, and water tested the boat and motor set up before purchasing a jack plate. I ended up not getting it for the reasons stated earlier. My stern was heavy enough already and the plate would have caused it to squat even more. I also have a problem with cavitation when its rough out. I couldn't put the motor any higher even if I wanted to.

I only have a 20hp and am guessing your 'stern squat' would be even worse than my set up. I also can do 20mph and that is plenty fast enough when running shallow, especially considering most of the time I am barely creeping when looking for reds. A jack plate would not have given me any extra performance, and if anything it may have made it worse. Not worth it for me, maybe others have had better luck.

[SHOWBOAT]

I'm on the other side. IMO not having a lower unit hang lower than necessary is crucial in our region. For a 16' with a 50hp I would probably look at a lighter/less expensive route (set back plate or manual jack plate). If you have pressure at the desired height, then you should be able to reprop, add a cavitation plate, etc to get the performance desired.

My 18' Xpress is lifted all the time. The only time I lowered it was when I got caught in rough seas. Now the pump has gone bad, and I bought a bay boat, so I'm totally fine lifted 100% of the time. It has an aggressive 4 blade prop and I don't have any blow out issues.

SG-your comments concern me a bit. My bay boat, with a pocket, is having a JP installed as we speak. I expect to be able to lift and run. I'm having some cupping added to the propeller, but I may end up with a different prop all together...

[silverking]

There are certainly benefits to having some of the accessories described. I have an Atlas electric jack plate, Bob's cavitation plate (Whale tail) and four-blade stainless prop on my skiff and all serve their purpose. The Mosquito will float in less than 6 inches with my normal load. I did not have a jack plate on my former 20-foot flats boat, however, as the flattened stern (11 degrees deadrise) allowed me to trim the motor and idle almost as shallow as the hull would float without one.

Still not convinced any combo will really achieve what RB is trying to do with the setup he described. Also trying to make the point to all who are just getting started fishing skinny water that it's better to go slowly and quietly and with as little noise as possible to get into prime fishing zones and minimize damage to the bottom (hull and flats).

Whenever my mechanic did a computer diagnostic on my engines he would always kid me about how many hours I had idling vs. faster speeds and WOT. Use the big engine to get within reasonable safe range, jack it up and idle some more and then get on the push pole or now more often for me the trolling motor. Believe that is what Redbelly is trying to accomplish as well.

[Salty Gator]

I'm on the other side. IMO not having a lower unit hang lower than necessary is crucial in our region. For a 16' with a 50hp I would probably look at a lighter/less expensive route (set back plate or manual jack plate). If you have pressure at the desired height, then you should be able to reprop, add a cavitation plate, etc to get the performance desired.

My 18' Xpress is lifted all the time. The only time I lowered it was when I got caught in rough seas. Now the pump has gone bad, and I bought a bay boat, so I'm totally fine lifted 100% of the time. It has an aggressive 4 blade prop and I don't have any blow out issues.

SG-your comments concern me a bit. My bay boat, with a pocket, is having a JP installed as we speak. I expect to be able to lift and run. I'm having some cupping added to the propeller, but I may end up with a different prop all together...

I’m not sure why mine is like that, but it is. 2 maybe 3” up is all I can run with. And it really slows down. I’m not looking to run super shallow. I like seagrass and don’t want to scar it up. It’s nice to have when idling down a shoreline, but it doesn’t do much for me in terms of running much shallower. I hope you get what your looking for. Im going to be re propping soon, possible a 4 blade and it may change

[Redbelly]

I'm on the other side. IMO not having a lower unit hang lower than necessary is crucial in our region. For a 16' with a 50hp I would probably look at a lighter/less expensive route (set back plate or manual jack plate). If you have pressure at the desired height, then you should be able to reprop, add a cavitation plate, etc to get the performance desired.

My 18' Xpress is lifted all the time. The only time I lowered it was when I got caught in rough seas. Now the pump has gone bad, and I bought a bay boat, so I'm totally fine lifted 100% of the time. It has an aggressive 4 blade prop and I don't have any blow out issues.

SG-your comments concern me a bit. My bay boat, with a pocket, is having a JP installed as we speak. I expect to be able to lift and run. I'm having some cupping added to the propeller, but I may end up with a different prop all together...

Exactly my feelings on damage control. Probably the best tunnel design I have seen was on the Scandy I had. With the right prop that thing jumped up on plane with a 4 stroke Yamaha 40 hp. It ran virtually with 2" of skeg below the hull. A HJP was a must with it's tunnel, as with any tunnel in my mind.

But.....it had a few cons, reverse, squat, cavitating in chop....

That's why I am looking at a HJP with a non-tunnel. Not to go racing about in 12" of water! But to not have to idle either, and damage control.

[Squirm88]

I have a 22’ pathfinder with a pocket hull and a jackplate. I can’t really run with my jack plate higher then a couple of inches without it cavitating. If I installed it to run shallower, I’d be extremely disappointed. I really only use it when idling in really shallow water. I know on some boats, you can really jack it up and still run, but not on all boats. Good luck

You have the wrong prop on your Pathfinder if you cannot run jacked up without cavitation. Most 2200V Pathfinders with jackplates are running Powertech OFX4 props.

[procraftwes]

You have to run dangerously shallow to turn the grass into salad and anything less would just be thrusted water into the grass which wont hurt it.

Those prop scars you see are from people who hit bottom.

Just sayin.

[Salty Gator]

You have to run dangerously shallow to turn the grass into salad and anything less would just be thrusted water into the grass which wont hurt it.

Those prop scars you see are from people who hit bottom.

Just sayin.

Hit bottom for miles?? Those prop scars are from people running to shallow

[Salty Gator]

I have a 22’ pathfinder with a pocket hull and a jackplate. I can’t really run with my jack plate higher then a couple of inches without it cavitating. If I installed it to run shallower, I’d be extremely disappointed. I really only use it when idling in really shallow water. I know on some boats, you can really jack it up and still run, but not on all boats. Good luck

You have the wrong prop on your Pathfinder if you cannot run jacked up without cavitation. Most 2200V Pathfinders with jackplates are running Powertech OFX4 props.

I believe your right, working on repropping very soon.

[silverking]

https://www.sabineskiffs.com/