? boat bounces in a sharp turn

[Shane]

Ok Ive got a new 17/52 Blazer with a 60/40 Mercury. My problem is when Im up on plane and start to make a sharp turn it starts to bounce.My old boat would slide around the curves. The only things that I see different between the two is that the old boat had two tabs on the back corners I think their called trim tabs or something. And the motor on the old boat was set a little lower. The new boat will run a little faster bout 3 mph. Can anyone think why this thing is bouncing?

 

[Shane]

Nobody has [-o< any ideas

 

[bulldog]

I have nothing. I have a 1848 and mine slides to the point of sliding out if I am not careful. It has gotten me scared a couple times but I know it well enough now that I can drive it to the point of scaring people. I'm interested to see what people say.

To start, what differences are on this boat compared to the last boat? Width, weight of boat, weight of motor, length, trim tabs, general balance of the boat. Does it bounce all the time or just when it is loaded down or empty? All of those things could play a role in the bouncing. Lets start eliminating things and see what we can come up with.

 

[Lil' Blue Rude]

I run a 16' 42" Blazer SS witha 40hp evinrude 2cylinder on it and I had the same problem the first year I run the boat. My motor was set to low in th water. When i would try to turn a left hans 90 degree turn the front right of my boat would pick up and slap back town. Vice versa on right hand turns.
When I mounted my motor it was a little to low in the water. I couldn't go up a hole because it was to far up and the motor cavitated. I had to slot two of my mounting holes together(motor mounting bracket) it's better to do that than redrill hole in the transom. Then you have to shim your motor height by laying paint stick on top of the transom. The good news of all that trouble is your boat will slide and you might gain some more speed. I set my motor height by laying something flat on the bottom of the boat right in front of the jet. The bottom of the boat should be slight above the cut where the grates lay. If you need any help with any thing or need me to explain myself better I am more than happy to try to help you.

 

[KRS62]

I am sure someone with knowledge will respond eventually, but I thought this is an "inherent" problem with flat bottom boats. You need something in the water with greater force than the centripetal? force. Boat rib, tab, motor, etc. I suspect that I tab could help, but suspect it could introduce negatives as well (slower top speed?)

KRS

 

[KMixson]

As you make a turn, does the motor cavitate at all? Does it lean to one side in the turn more than your old boat did? If you make a turn and the motor cavitates (from the prop being too high) the boat will slow down and then as the prop catches again the cycle will start all over again. How much weight is in the boat? Do you have all of your gear in it? A heavier boat will not be as likely to bounce around as a lighter boat.

 

[Shane]

They are the exact same boat had one for 3 months and wrecked it while in tow. The only thing that i see different is the trim tabs. and i think the motor is just a touch higher. The old boat would slide around the curves and yes it would scare a lot of people.lol It does seem to jump like the left corner up and then down and continues to do so until I let off of get out of the turn. The weight is about the same I didn't have a cooler, and usually do.
This boat will definetly outrun the old boat and that may be the problem may just be running faster so therefore turn differently, Do yall think the trim tabs would have slowed the old boat down that much if so I may just live with it and not give up my topend. Thanks for all input I'm still very new to this jetboat stuff.

 

[fender66]

Could be the way the tabs kept the boat in balance as you skimmed across the water. I don't have that problem though so just a guess.

I'm running a 1756 Alweld with a 225 Merc Jet. When I hit a turn, it slides for sure. :shock: I don't have the tabs that you mention, and I think you are referring to tabs that are on the back corners of the boat. I do have a whale tail on my jet though. Have run with and without it, and it makes a HUGE difference! Here's a link to the place that made my whale tail.

https://www.trouttandsons.com/AquaBoss2/aq-show.php?listid=119039427568067&page=11&p=5&s=make%20ASC

 

[Shane]

Ya those tabs are on the back corners of the boat.I looked at them whale tails what can u tell the difference is jumping on plane quicker, or control. They look cool I'll give em that.

 

[fender66]

Control is the part of the reason for them.....but they pull my back end up on plane faster and get me out of the hole quicker.

 

[Shane]

What about speed with that little 60/40 do u think it'll slow me down any? I know hard to have your cake and eat it to but it sure would tast good.

 

[Lil' Blue Rude]

I am sure someone with knowledge will respond eventually, but I thought this is an "inherent" problem with flat bottom boats. You need something in the water with greater force than the centripetal? force. Boat rib, tab, motor, etc. I suspect that I tab could help, but suspect it could introduce negatives as well (slower top speed?)

KRS

oh yeah I don't know anything about this problem do I? [-X Like I said I had the same problem on my boat and I don't have a spray plate,whale tail or trimtabs. There's two reasons a flat bottm jon boat jumps in a corner you have your motor trimed to high or the motor is mounted to low in the water. My dad owns a 17' 52" blazer with a 60/40 merc and it don't have trim tabs and it will slide. If the motor is raised up the problem will stop or at least get better. I think I would know something about an outboard jets perfomance considering I set my boat up, do all the work and it runs 41mph on the river. Find me two cylinder that don't have Luttrel part in it that can come close.

 

[reccrew]

If it's happening on downstream only, your motor is too high.

 

[Shane]

Thanks guys I'll play with it a bit more. Maybe I'm trimming to high.

 

[Lil' Blue Rude]

I don't think it is because the motor is trimmed to high. My dads 17' 52" blazer has the motor set a hair to high and it won't bounce at all. You can trim it up till it cavitates and it won't bounce.

 

[Shane]

Im going to play with it a little sat if the weather is permitting. Current River I haven't had any trouble yet but 11 point the river is more narrow and the turns are sharper,and shallower and most of my running is going to be on Current so after some getting use to.

 

[Seth]

Man I have no idea. Every jet rig I've road just slides when you cut it hard. I've also got the trim tabs on the back corners on my boat and it slides pretty good, but not as bad as a boat without them I don't think.

 

[fender66]

Please post your results Shane. We all want definitive answers for things like this.

 

[Codeman]

I am sure someone with knowledge will respond eventually, but I thought this is an "inherent" problem with flat bottom boats. You need something in the water with greater force than the centripetal? force. Boat rib, tab, motor, etc. I suspect that I tab could help, but suspect it could introduce negatives as well (slower top speed?)

KRS

oh yeah I don't know anything about this problem do I? [-X Like I said I had the same problem on my boat and I don't have a spray plate,whale tail or trimtabs. There's two reasons a flat bottm jon boat jumps in a corner you have your motor trimed to high or the motor is mounted to low in the water. My dad owns a 17' 52" blazer with a 60/40 merc and it don't have trim tabs and it will slide. If the motor is raised up the problem will stop or at least get better. I think I would know something about an outboard jets perfomance considering I set my boat up, do all the work and it runs 41mph on the river. Find me two cylinder that don't have Luttrel part in it that can come close.

Hey man I don't think he was aiming that at you. We try not to throw a bunch of attitude around in this forum, I'd kind of like to keep it that way. Thanks for trying to help him.

 

[turne032]

my experience has been, when a boat starts to bounce, it is trying to get up out of the water more, but the weight of the boat pulls it back down. In every case this picks up speed. usually around 1.5 to 2 mph.

in turns, most of the time in rivers, the water is shallower and has more pressure between boat and the bottom of the river. This creates more up-force for the boat sometimes causing the boat to bounce. about 90% of the people i know like their boat to bounce, but i know hard it is to control and how rough it is to ride in. The hight of your motor plays into effect with bouncing as well as the trim angle.

if you want to maintain speed, i would adjust the motor height, and mounting angle with wedges. Trim tabs and whale tales will cause your boat to slow down. People claim that they do help with getting your boat on plain faster ( i do not doubt their statements) but they do reduce speeds around 2-3 mph.

You have to weigh what benefits you in your situation as to what the right action to take is.

I would rather have the performance. I believe that If I gain mphs, i will gain a faster plain. I would rather balance my boat, this does not mean you should place batteries or gas tanks to the front, but start moving things 6 inches at a time, maybe moving the drivers and pasenger seat up 6 inches forward can change the way a boat handles and performs. I would defenitely try moving my motor around to find the sweet spot. That may take time and several different trial combinations, but motor placement and boat set up is the most determining factors to get an outboard jet to run properly.