Motor for 12' Hi-Laker

[CopperFox]

I currently have a 12' Hi-Laker with an 8 hp Evinrude engine. The engine starts first pull almost every time and I have just had the water pump completely redone. I move at a good speed but the motor isn't enough to get me on plane. A 20 hp is the stated max. What is the minimum size I would need to get on plane? Ideas?

 

[steelespike]

There is a 2 hp jon boat on you tube that planes.You might need a tiller extension so you can be in the middle seat.
The 8 hp should make about 12 or 15 mph on a light reasonably fast boat.
A 9.9 about 20,and a 15 about 22 or 23.Evinrude and Johnson made a 9.9 and a 15 that were basically the same motor.
A 20 will seem like its going to fly.

 

[CopperFox]

Hi Steel. Thank you for your reply. I do try to keep a lot of weight forward, including the gas tank, but don't sense I'm near planing, and so I accept that more power will be required, regardless. I too have heard that 9.9s and 15's can essentially be the same motor. But with 50% more HP, does that not translate to significantly more speed? Your numbers would indicate not, and I have heard that elsewhere. Going from 12-15 mph to about 20 is significant, and might be all it takes to get on plane. If going to a 15 hp will only likely get me another 2-3 mph, maybe a 9.9 is a better bet. I understand these are all rough estimates but maybe I can get away with a 9.9 hp and not have to spring for a 15 hp. It is that thinking that lead me to post here. Let me know if my thinking is flawed, anyone. Thanks.

 

[Frank Acampora]

Something just niggles me "wrong" about your problem. How much junk are you carrying that your 8 can not plane the hull? Is the engine running at full horsepower capacity?

When I was young, oh, 50-60 years ago, we had a cabin on a horsepower restricted lake. With only 5 1/2 horsepower all the kids had 12 foot tin boats except me. My parents wanted something substantial to ride in so I had a 13 foot closed bow fiberglass runabout. ALL these boats, including mine, were able to plane with 5 1/2 horsepower. Of course, this was with no weight and only the operator and a 6 gallon gas tank.

 

[steelespike]

I too wondered about your lack of being on plane.Have you adjusted the trim?
You wouldn't be the first one to not realize you were on one cylinder except for the lack of power.
The 5 1/2 Frank mentioned is capable of about 12 mph.We had one on a flat bottom 12ft. steel boat.
With a 180# driver it popped on plane and made about 10 or 12 mph.with a tiller extension.
Do keep in mind that these are estimates and what amounts to guesses.The faster a boat goes the harder it is to increase speed.
Some of the 9.9s are rated up to about 6500 rpm some 6000.The 15 is rated up to 7000 rpm.The motors use the same basic size prop
The 9.9 just turns less rpm.The 15 with more power could run more pitch compered to the 9.9 for similar applications.

 

[CopperFox]

Well, 'junk' is in the eye of the beholder. I do tend to have more than just me: battery & 50 lb thrust electric trolling motor, oars, 2 fishing poles, a tackle box, a fishing net, a Sterlite box with flashlight, night running lights, walkie talkies, etc., oh yes, and a 6 gallon tank of gas. So it is far from empty, but there is really nothing you'd not expect if you were using it to fish. I haven't tried but if it was only me and the gas tank, I suspect the boat still wouldn't plane, regardless of where I sat. This is a fiberglass boat, and Hi-Lakers are known for having higher sides than most boats, so maybe it weighs more than the average. The engine is a late 80's model and it doesn't move me much faster than my friend's identical boat with a 6 hp on it, so maybe the motor is just showing its age. If that's the case, maybe a 9.9 Hp in slightly better shape, would do the trick.This is encouraging. Thank you.

 

[CopperFox]

Steel: Thank you for weighing in as well. I was writing my last when yours was posted and so I only just saw it now. Having two people come to the same conclusion certainly makes me think I should be getting better speed. I was quite serious saying I barely beat my friend with a 6 hp on the same boat. I'm thinking it is not using just one cylinder as I just had the water pump replaced by a professional and he never mentioned it. The trim is definitely a consideration. I really like this motor - starts first pull almost every time, and as noted, the whole water pump is new. Since I bought the motor with the boat, I just assumed it was properly adjusted. I will have to educate myself on how to do that, make any changes, and report back next time I am out with it. Thank you both very much for taking the time and sharing your knowledge.

 

[steelespike]

If you want to try to pep things up there are some things we can do. Check the prop size.Near the base of the blades or on the hub somewhere.
Something like 9" X 8" there may be a part number.
Does it start easily and run smoothly? Check to see if the carb opens all the way and the stator advances as it should.
While your boat may be heavy compared to aluminum sometimes are easier to push.once planed.
If you want to test it Take everything output the safety gear. Move the tank forward. Try each trim setting make a note for reference.
The anti vent plate(just above the prop) should be about even with the bottom.Won't help much but might be the difference between
or not once everything is setup.
Use a GPS to clock your speed.Usually available for a cell phone.
Should have a tach but we can probably get an idea about the rpm with an accurate gps speed.

 

[CopperFox]

I was thinking the prop might not be ideal as well. It is not damaged, but it might not be the best for the job. I'll have a look for that prop number.

The motor starts and runs like a dream, despite its age, which makes me reluctant to part with it if I don't have to.

The tank is already at the front and I was thinking of splicing in wiring to put the battery there while running the trolling motor.

I was really encouraged by the suggestions to check trim settings and so will definitely do that and have suggested it to my friend with the 6 hp as well. I have Maverick as a GPS app for my phone and so far am happy with it on the water, though I have not used it to measure speed. That's a good suggestion. It is supposed to pour this weekend, but as long as it isn't windy, I'll get out and see if I can coax some more MPH out of my 8 horse. Thanks again for all the suggestions. They are appreciated.

 

[fishin98]

With your boat on the trailer, and level, look at motor, is it straight up and down, if so, move your trim up 1 or 2 notches, then try it out. Look at your prop, on the hub there should be some numbers ending with a number with a P. A motor that size most likely be running a 8P. A 8hp motor is not going to be a speed demon anyways.

 

[CopperFox]

Disappointment! Correct me if I am wrong here but if the bow tends to ride up and I'm wanting it to plane, I need to have the motor set as close to the boat as possible, or at least closer than it is currently, to pull the bow down. Well I checked last night and it it is on the 4th hole, making it as close to the stern as possible.

Fishin: You think 'up' could help? If that's the case, I have plenty of wiggle room there, but not sure that's what I'm wanting.

Next is the prop. With the light I had, I couldn't see a number, or even feel one stamped on the prop. I will have to check again with better lighting.

The weather's predicted to be miserable this weekend, but if I can get out I will try to get a speed GPS reading off my phone and see if I can notice a speed difference with each of the trim settings.

Thanks for everything so far, everyone!

 

[steelespike]

The Hi Laker 12 is 195 lbs and is 5'5" wide. Quartermaster 12 is 170lbs and 4'5" wide.
Some aluminum utilitiesI I checked rated for 20 hp or more were 200 to 240 lbs .
Maybe you could post some pictures.

 

[CopperFox]

Not a problem. I'm not quite sure what you're looking for. Just general boat/motor combo?

 

[fishin98]

You are going to have to have a certain amount of bow rise to get the boat on plane....with the bow plowing into the surface you will never get it on plane. With the bow up a bit, it will allow the hull to get up on the surface of the water, once the hull achieve's that, THEN the hull can level out, wilth the bow still above the surface.

 

[steelespike]

Is it 4'5" or 5'5" wide?I did find a picture that seemed to indicate a lot of rocker (bow to stern curve)
Does it have hard chines L or soft J,
Flat bottom, like a jon boat?

 

[bassman284]

I goggled pictures of this boat and I'm not at all surprised that 8hp won't get it on plane. My guess is it will take at least 15hp to get it on some kind of plane. The bow is coming up because it's a planing hull and it wants to get on plane and will try do so but needs a certain minimum speed to do so. Pretty sure you'll never get that speed with the 8.

My experience: I have a 17' Lund rated for 75 and carrying a 60. When I get it out on the pond and drop the hammer, I get on plane in about 2.5-3 seconds. I've done some playing around with it and if I start slowly opening the throttle the bow will raise higher and higher until I get to about 17 or 18 mph. Then the bow will start to come down as I get into a kind of "plowing" plane. In other words, the boat is leveling out but still down in the water a bit and putting out quite a bit of wake. At about 22mph I get higher in the water and start what I would call a "skimming" plane. At that point I can ease back until I get to about 18mph at which point the boat sinks back down and the bow starts coming back up. After 22mph, the faster I go, the less boat is in the water.

I started experimenting after I put a 9.9 kicker on (a lake I like to fish has a 10hp summer limit.). I was hoping to get about 9 or 10 mph but could only get about 6 1/2. I asked the dealer about repropping but he told me it wouldn't really help. He told me that the bow was coming up because the hull was trying to plane but the 9.9 didn't have the ponies to do it.

tl;dr, the bow is coming up because the boat wants to plane but you don't have the horsepower to put it over the top.

 

[Sea Rider]

With you alone, lightly loaded, move your weight forward, place fuel tank up front, trim engine at 90? for boat to ride parallel to water surface, if planes, install an induction tach, go for a wot spin on calm flat non windy water cond. Check achieved max wot rpm and compare ti to its factory wot range, can go from there maximizing a less prop pitch tu pull your revs up near max stated rpm for combo to plane much faster.

Happy Boating