jon boat plowing at high speeds

We have a 2018 triton 1860 Mod V with a 2013 60 HP mercury with a 13 pitch stainless prop on it. We also have a jack plate for running in the shallow water. No matter where we trim the motor the front plows the water and if there is a chop on the water we get a constant shower. I can trim the motor up to the point it is cavitating badly yet the front just does not come up. We also have 95 smoker craft mv1750 with 2010 40 HP mercury and that one performs great. You can trim that one up and the front comes up as it should. We are baffled by the performance on the triton. My first thought is the prop is too small and is not grabbing the way it should. What is everyone’s thoughts? Thank you.

My guess is the jack plate has the motor up to high so that when you trim the motor up it comes out of the water instead of raising the bow. And/or there is to much weight in the bow.

Thank you for your replie, we have marked the jack plate so when normal running the motor is set to Mercurys measurements for the cavitation plate related to the bottom of the boat and there are just two batteries for the trolling motor up there. The boat can be empty and still run this way.

jake920920 wrote:

1860 Mod V with a 2013 60 HP mercury

60 hp outboard seems quite undersized for almost a 19 foot boat. My boat is 17 feet, 8 inches and it has a 75 hp outboard. Perhaps there just isn’t enough power.

Thank you, my other jon is a smoker craft mv1750 and that is 19 feet long with the pods and that has a 40 HP on it both boats run at wide-open 30-35 MPH depending on how much weight you have in them.

gimruis wrote:

<div class=”d4p-bbt-quote-title”>jake920920 wrote:</div>
1860 Mod V with a 2013 60 HP mercury

60 hp outboard seems quite undersized for almost a 19 foot boat. My boat is 17 feet, 8 inches and it has a 75 hp outboard. Perhaps there just isn’t enough power.

That’s a 1000# hull and close to 19′ long. I’d say you’re underpowered.

Did you ever drive the boat before installing the jack plate? In other words can this problem be traced absolutely to the addition of the jack plate?

I know this next one is difficult to determine without making some measurements, but does the angle of the jack plate’s mounting surface run roughly parallel to the surface of the transom? In other words, if the outboard were mounted on the transom, would the angle of the prop thrust be the same at a given trim level as if the outboard were mounted on the jack plate? I’m wondering, did the jack plate somehow change the angle that the outboard hangs at.

BTW, I know this is IDO and the solution to every problem is to add 300 HP, but I don’t buy that a 60 HP cannot get the big, flat bottom of a mod v on plane. If I can get a 500 pound deep v with 2 guys to run 24 MPH with a 25 HP, there’s no freaking way he shouldn’t be able to plane out a mod v with 60 unless he’s using it to haul cement blocks.

Grouse

I have not measured that but will. Visually it appears to be parallel and the tilt trim should take care of any angle issue. We bought the boat with the jack plate on it, so no we have not experienced it without. LOL 300 HP that’s funny, the smoker craft has a recommended max HP of 45 and the trition info plate has been painted over by the previous owner. It does not take much to get a jon boat up on plane. The primary use of these boats are for duck hunting and being able to trim the front up is to handle the rough waters we travel in is kinda crucial. Now the 60 has the same size prop as the 40 does, from what I have read that is not unusual. The motor just seems to cavitate easily and through the trimming process, it never starts to porpoise across the water IE when the trim is too high. I just keep going back to possible the prop is to small.

Take a quick look with the motor down out of the water, your cavitation plate or the larger plate going around the lower unit should be level with the bottom of the boat.Sounds to me like the motor is too low.If it isn’t, adjust accordingly, and re-run it before adjusting the prop size.This will drastically affect speed,trim prop size,etc.Too low and the boat will drag, too high and planing issues occur.Also check the shaft length is correct for your transom.

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Transome and shaft are correct, mercury manual calls for 0-1″ for the cavitation plate below the bottom of the boat. We will double-check all measurements and try it again. The previous owner pruned the skag off and we are assuming he ruined the prop too. So he may have just put whatever prop he could get that was close. One would hope he would have bought the correct replacement prop.

Yikes. So back up a little bit here. Do you know the prop on it is a 13 pitch because that’s what it says stamped on the prop? Or are you just assuming that because that’s what the oem spec is?

Have you actually measured the diameter of the prop?

Also have you checked for a spun hub?

Grouse

What rpms are you running at when throttle is wide open? Sounds like you have way to big of prop.

Just a comment on props. If you are going to try a new prop, try a 4 blade. This will give you a lot of bow lift without having to trim up as much.

-J.

Stamped 13P, I will measure it. How do I check for a spun hub? It is a tiller so there is not a tach. We were looking at options and that was one for a 4 blade.

the prop is 11 1/8″ it is a solas 1331-111-13

Well you can get a tach hooked up pretty easy on that new of motor, rpms are gonna be important start. I would say that prop is to large. But so many variables,.

I would like that on both boats, it is not as easy to tell RPM by ear with the 4 strokes.

Might want to find an install manual for the jackplate, if it sets the motor back from the transom, it might require the motor to be higher than if transom mounted

I will see if I can track one down. Thank you.

From Mercury prop selector. 18′ flat boat boat with 60 hp merc

Propeller Material Blades Diameter Pitch Rotation Part #
Black Max® Mercalloy 3 10.875 11 RH 85632A40
Black Max® Mercalloy 3 10.625 12 RH 73134A40
Black Max® Mercalloy 3 10.75 12 RH 816702A40
SpitFire® Mercalloy 4 10.6 12 RH 8M8026625
Trophy® Sport Stainless Steel 4 10.625 12 RH SS-878612A40
Vengeance® Stainless Steel 3 11.63 11 RH 823478A5
Vengeance® Stainless Steel 3 11 12 RH NF-855856A5

Thank you I was looking for that. Where did you find it?

A 60 horse should push that boat without issue. As long as its not severely overloaded.

My friend’s carp boat is a 21ft tracker grizzly with pods, 8ft front deck and 6ft rear deck, 4 batteries, 2 adults. Heavy old boy and it runs on plane at 38mph with a 90hp merc. It’s very impressive, and I wouldn’t believe it without having been in it while we hit that speed. So what I’m saying is you may be under-powered but I doubt it and ultimately agree with grouse, there’s probably some other issue at play.

KPE wrote:

My friend’s carp boat is a 21ft tracker grizzly with pods, 8ft front deck and 6ft rear deck, 4 batteries, 2 adults. Heavy old boy and it runs on plane at 38mph with a 90hp merc. It’s very impressive, and I wouldn’t believe it without having been in it while we hit that speed. So what I’m saying is you may be under-powered but I doubt it and ultimately agree with grouse, there’s probably some other issue at play.

I know my 40HP does a good job on my grizzly 1654 even when the prop was SS with too much pitch, it just didn’t get on plane as quick or run the proper RPMs when wide open. With a motor too low on the boat you normally can’t keep the bow down and have some steering torque in one direction

Need a tach to verify WOT RPMs.I am guessing a 12″ pitch Spitfire will put you in the zone.Engine needs to run at recommended RPM range to produce rated HP.Even better if you have a decent dealer that has a prop exchange,you can try out different props as long as you don’t damage them.

The prop on my 40 is almost 1″ smaller same pitch. We will try to run that one and see what happens.

jake920920 wrote:

We also have a jack plate for running in the shallow water. No matter where we trim the motor the front plows the water

How beat up is the bottom of the hull from running shallow water? Has the bottom been deformed, even slightly? Especially directly ahead of the transom. Even a slight “hook” in the hull can keep the bow down. The “hook” acts as a permanent trim tab, keeping the bow down.

The illustration is just an example pulled from the internet. Like I said, it does not take much hook to create the effect.

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we do not run our boats like all the youtube videos LOL. They are very straight no dents no issues like that what so ever. Thank you for sharing that illustration

jake920920 wrote:

we do not run our boats like all the youtube videos LOL. They are very straight no dents no issues like that what so ever. Thank you for sharing that illustration

Jake, a little sensitive, eh? You bought the boat used, the damage might have been done long before you got involved.

Also, Solas props aren’t all that good. Put a 12″ Spitfire on it and let us know the results.

HRG

NO not sensitive at all, my attempt to be funny was not funny to you. Oh well. No, I am just stating we do not log jump rock skip beach our boats at WOT like you see these guys do on youtube. As stated the bottoms are straight without defects so that will not be the issue and yes I have looked at the bottom of the boat.