Top end question

[sneak_e_pete]

I have a 14 ft princecraft with a 2011 20hp yamaha 4 stroke. With just me (and I am a hefty guy at 260), I get top end of 30 km/ph. Seems slow to me. Boat is max rates for 20hp. Thoughts?

[mike rousseau]

30km/h or 18.6 mph seams like a good speed for a 20hp 4 stroke...

[mattaw]

My thought as well, seems reasonable for the motor size...

[scugpg]

What style of boat is it? (3 bench or full floor/casting deck etc?). I have seen up to 22mph/35kmh with that motor in a 14ft with floor, casting deck, bow mount motor and two batteries. Similar person weight in boat.

Edited November 16, 2014 by Spooled

[Fisherman]

You may get a couple more km/h by trying different trim positions.

[porkpie]

I have a 2 stroke 20hp yamaha and can do 25MPH gps with just me and a couple rods and a tackle bag, Starcraft SF14. I weigh 25lbs less than you. Seems a bit slow to me, that is comparable to the speed I was getting with a 15hp 2 stroke.

Edited November 16, 2014 by porkpie

[mattp33]

is this a tiller? I am going through set up issues as well and I can only imagine trying to get max speed with the very little setup a tiller allows you.

[Sinker]

When your talking 20hp motors, any improvements are going to be so minimal its hardly worth it. I'd say your doing fine with what you have.

 

S.

[northernpike56]

2 strokes are faster. In a 14 ft aluminum dingy I have done 41 km/h with nothing but me, the motor, and gasoline (I only weigh 140 lbs though). This was with a merc 15 hp 2 stroke.

[northernpike56]

When I buy an outboard for my canoe is will be a 4 hp 2 stroke guarenteed

[wormdunker]

Seems a little slow to me. I recently purchased a new yammy 20 hp, 4 stroke, electric start. I have a 14' Lund with full floor, tackle bag, 4 rods, full tank of gas, Electric bow mount & 2 batteries. I weigh 215 lbs & I get 23 mph. If I have my partner in the boat - he is 240 lbs, it slows down to 18 mph.

[scugpg]

The boat i referenced @ 22mph - dry weight was over 500lbs not including gas, bow mount, batteries, tackle, people etc and can get over 23mph at times.

 

Safely raising the motor to optimal height on the transom and experimenting with props (using a tiny tach) helped optimize the setup. In small short heavy boats they are also tough to get on plane as they can be very stern heavy.

 

There may be circumstances where you require more than one prop depending on the load situation in the boat as it can vary the top end motor rpms significantly and you could over rev.

 

These are great and a place in Mississauga is a Canadian distributor http://tinytach.com/gasoline.php

Edited November 16, 2014 by Spooled

[Roe Bag]

Had an F20 Yamaha on a 14' Misty River.. Standard factory supplied prop. For whatever reason the F20 is about 2.5 inches longer than the 25 Yamaha two stroke that I replaced. I cut a piece of 2X2 the width of the mounting bracket. Placed it under the bracket. This raised the anti cavitation plate so it was just slightly below the bottom of the boat.

The less motor you have in the water the less resistance. Once you find your sweet spot, drill holes and bolt the motor to the transom. In the meantime make sure the thumb screws are good and tight and secure a safety chain.

Three adults and all of our gear it ran out at 17-18 mph. With that load I ran the tilt pin in the third hole up from the bottom. Otherwise the boat is plowing.

Solo with my gear it ran out at 23 mph. I had to lower it to the second hole from the bottom, otherwise the boat would porpoise.

I would also intentionally move as much weight forward as possible. This also assisted in preventing porpoising.

Ideally you want as much boat out of the water as possible.

Tilting the motor out and away from the transom forces the back end down and lifts the bow.

Too much and the boat will porpoise. Not enough and the boat will plow.

Experiment until you find the balance. Once you do I think you will be pleased.

14' Misty River. Dry weight 305 lbs. Bench seats. No floor. Bow mount electric and series 27 deep cycle battery.

F20 manual start. Three swivel seats. Gear. Plus me at 230 lbs.

23 mph.

The 25 Yamaha two stroke ran out at 25 mph solo. 21 mph with three.

Smaller boats are load sensitive. Proper trim and balance are the key.

Edited November 16, 2014 by Roe Bag