Outboard Performance

[Wood Shampoo]

I am in need of some advice from our vast jet sled population here at ifish.

Here is my question. I have a 16' flat bottom sled that is powered by a older 50 hp Mercury outboard that has been converted to be a jet. With the 3 people and limited gear in the boat, it will only do about 12 mph via the GPS.

Is this about right or should I have someone look at the motor/jet? Any suggestions?

Thanks in advance!

[Pilar]

That sounds pretty slow. What happens when you are alone? Can you plane out? Also remember that a jet is less efficient than the prop drive. I think the cut is 25%.

The only other thing I can think of is trim. Is the trim adjustment a rod you move or hydraulic? Try different settings and see what happens.

Other than that I'd say you need more cajones on your transom. A 50, even a 'blackmotor' sounds small for a 16' sled.

[Wood Shampoo]

Pilar -

Thanks for the info. With two people in it, it can plane and with only myself, it is no problem. The trim is not hydraulic and I have never play around with it. What angle sould the water coming out of the jet be?

[ 09-17-2001: Message edited by: wtbarrong ]

[FishinMission]

Best 'o my knowledge says you lose 35% with a pump....so if I do the math...that means your 50 is putting out 32.5hp. Not enough "beef"...er I mean horsepower if you ask me. Might be better with just yourself, but probably still not enough for a load. Sorry.

[ 09-17-2001: Message edited by: FishinMission ]

[Dogfish]

WT,

Is that 12mph a landspeed when going upstream, downstream, or on a flat calm lake with no current? That would make a difference.

Play with the trim until you find the highest speed available.

[Phil Layer]

I've got a 16' sled with an older Johnson 70 hp with jet on it.

Three people on board mine means crawling to the holes. Two on board is a nice clip but that third one just seems to be too much.

[Wood Shampoo]

12 mph was going downstream in the Columia. What should the trim be set at? Strait, little up, or a little down?

Allnite45 - Where you fishing on the Columbia below the Sandy on Saturday with your son? Your discription sounds like the boat that was next to us on Saturday.

[FishinMission]

Next time you're on the water, mess with the trim if you can. You should be able to find the "sweet spot" so to say. I'd start with it "level" and go from there. Where is your weight displacement?? Everybody in the back of the boat?? Everybody up front?? If you can...try and even out your load. Mine does best with the weight evenly distributed, but then I got 150 more hp. images/icons/wink.gif

[wetaline]

a little down will pop you up faster.. a little up will gain you faster speeds once on top...

[Bait O' Eggs]

Look inside of the intake and see what the gap is between the impellor and the sleeve.

It should be quite tight. I was told get the gap between 10 to 20 thousands. Maybe you are due for a new sleeve and a shimming. As the sleeve wears out and the gap increases, you loose performance.

I recently had the shoe off the bottom of my motor removing some rope images/icons/rolleyes.gif from the impellor area, and I was really surprised how much my new sleeve (less than a year old) has worn. It looked like a worn out brake drum with big grooves cut in it.

[Nanook]

If you don't run water that needs a jet, don't buy a new motor, try a prop on it first and then go bigger if you have to?

Man, that 200 HP new Merc jet sure is nice though. The 90 HP prop on my old Willie 20 foot Predator was plenty, but a 90 HP jet, would not have cut the mustard, for example.

[WaterDog]

I had a 16 foot sled at one time with a 40hp merc prop. Would do 30+ mph. Thought a pump would be neat and so what if I could only do 20 mph, I don’t go that far anyway. Found a pump, bolted it on, took it for a ride, came back home, unbolted the pump and put the prop back on. images/icons/rolleyes.gif There is nothing you can do, the motor just doesn’t have the ponies.

There is no substitute for cubic inches. images/icons/grin.gif

[Phil Layer]

WT- Wasn't me in the Columbia with my sled. I run mine on the North Santiam. For the Columbia, I've got a fiberglass boat.

Good luck!

[Wood Shampoo]

Does anybody have an idea where I could find a lower unit for this older (early 70's) Mercury 50 hp? Also, what would it take to swap the jet out with the prop (any additional parts besides the lower unit)?

[IAMFORELK]

You might try Oregon Outboard Salvage.

I also have a 15' sled with a 45 HP Mercury jet too. And you are absolutely correct, with one or two people...no problem. Add the third person and crawl to you favorite spot.

[fishbait]

Your boat is underpowered to begin with...

"Older 50 hp merc w/pump" equivelent to "older 30 - 35hp w/prop"

Check BOE post as to impeller clearance....this is important as to performance, and remember, no matter what, you do not have enough ponies to get that boat up on a plane w/three people.
I fished last week in a 18 ft Koffler, 6 ft wide bottom with an older 150 and it was doggie to get up on a plane.....
my 2 yr old 18 ft w/115 and three people is slow to come up on a plane.

[fop]

IAMFORELK, Do you have a phone number for OR. Outboard Salvage? Also what city are they located. I am in WA.
I'm looking for a lower unit for a 90hp Yamaha. I want to take off the Jet and go prop.
Thank you in advance, fop

[Wood Shampoo]

Fred,

Oregon Outboard Salvage http://www.outboardsalvage.com/
(503) 777-1548