Tiny boat performance help

[kalebsheridan]

Hello everyone,
I've been working on a tiny boat project that I could use some performance help with. I bought an 8 ft jon boat for cheap to use as a truck bed boat for my local lakes. I have a 5hp mariner that I use, and the boat is pretty fast at top speed, but takes forever to get up on plane, maybe 10-12 seconds. I build a jack plate to get the motor up higher (vent. Plate flush with the hull) and didn't seem to improve hole shot much. I've played around with weight as well, and I noticed I do come on plane faster when I lean as far forward as possible. Any tips for how I can get the boat to plane faster? Not exactly a necessity but man would it be cool.

 

[airshot]

You just proved to yourself that it needs weight is needed forward. The small hull is having difficulty getting up on plane due to the small area. Bigger boat or weight forward to balance that heavy motor. You would provably be just as fast or faster with a 10' Jon boat as the bigger hull will plane more quickly.

 

[jimmbo]

Does that Motor have an External Fuel Tank? If so, place it and your Anchor in the Bow
You could also move the Tilt Pin as Close to the Transom as the Holes allow, that will help the planing, but will likely reduce top speed

 

[Stinnett21]

Nauticus makes trim tabs for boats under 16' or try a device that attaches to the vent plate (if they make them small enough).

 

[mr 88]

Google, 5hp Mariner tiller extension, this will solve your planning issue by allowing you to sit in the middle seat while you plane out .

 

[Scott Danforth]

A piece of PVC pipe for a tiller extension

Also add trim tabs to extend the running surface

 

[kalebsheridan]

You just proved to yourself that it needs weight is needed forward. The small hull is having difficulty getting up on plane due to the small area. Bigger boat or weight forward to balance that heavy motor. You would provably be just as fast or faster with a 10' Jon boat as the bigger hull will plane more quickly.

That's true, I just don't want to be sitting in the front seet of I dont have too. It's funny, I just had a 10 footer I sold recently (crazy narrow and tippy so I sold it) that I was doing 22 mph in and planed great. I attributed it to that boat being longer and more forward heavy.

 

[kalebsheridan]

Does that Motor have an External Fuel Tank? If so, place it and your Anchor in the Bow
You could also move the Tilt Pin as Close to the Transom as the Holes allow, that will help the planing, but will likely reduce top speed

Yup, and I did that which probably helped. Strapped the tank to the bow. I'll try the motor tilted all the way down but the transom has some negative angle to it so the prop may be pointed slightly down. But I can try that.

 

[kalebsheridan]

Nauticus makes trim tabs for boats under 16' or try a device that attaches to the vent plate (if they make them small enough).

I was curious about trim taps, I can probably make some.

 

[matt167]

Principle of a teeter totter. The motor is going to push the stern down so it’s going to plow water until it can overcome that. If you equal the weight and equal the teeter totter more, you get a straighter forward motion. This is why most of the plastic bass boats have sliding seats

 

[kalebsheridan]

Google, 5hp Mariner tiller extension, this will solve your planning issue by allowing you to sit in the middle seat while you plane out .

I did make a tiller extension so I can sit in the front seat. You can see over the bow which is kinda funny. Helps a ton I just don't want to sit that far up front if I can find a way to plane out otherwise.

 

[kalebsheridan]

Principle of a teeter totter. The motor is going to push the stern down so it’s going to plow water until it can overcome that. If you equal the weight and equal the teeter totter more, you get a straighter forward motion. This is why most of the plastic bass boats have sliding seats

Basically what I had to do. I layed a board across both seats running bow to stern, and balanced it to where the boat was not off canter, and when I wanted to plane I moved all the way forward, and when I was on plane, I'd scoot back to where I was more comfortable. Maybe I'll make a sliding seat so I can do that more easily.

 

[kalebsheridan]

I do plan on adding some storage compartments in the bow, which will hopefully make the boat more forward heavy. That should help with planing as well but I am going to be running into the weight limit at some point. Maybe next time I go out I'll clamp an electric trolling motor to the bow and see if that weight helps.

 

[kalebsheridan]

Just for grins & giggles, here's a video of me nearly going top speed.

 

[redneck joe]

Just for grins & giggles, here's a video of me nearly going top speed.

No link

 

[mr 88]

That's true, I just don't want to be sitting in the front seet of I dont have too. It's funny, I just had a 10 footer I sold recently (crazy narrow and tippy so I sold it) that I was doing 22 mph in and planed great. I attributed it to that boat being longer and more forward heavy.

And what motor HP wise , was hanging on the back ?

 

[tpenfield]

I have an 8-foot pram with a 7.5 HP outboard . . . similar situation with planing.

Weight shift will help, but you may want to make some static trim tabs out of marine HDPE board (starboard) and stick them on the transom.

 

[Texasmark]

Yup, and I did that which probably helped. Strapped the tank to the bow. I'll try the motor tilted all the way down but the transom has some negative angle to it so the prop may be pointed slightly down. But I can try that.

What do you mean "transom has some negative angle"? If the top of the transom tilts back slightly, that's normal. That tilt would be beneficial to any tilt pin adjustment. If it's toward the boat, most unusual, then you will certainly need to move the tilt pin farther out.....maybe all the way to get the thrust angle to bring the bow up.