Upgrade Outboard Motor

[sailorb12]

Hello all. I have a SeaNymph 1991 with an Evinrude 15hp. I’m thinking of upgrading it to get away from a 2 stroke engine and just more power. It’s rated to go up to 35hp, but these days outboards are over 215lbs. How do I find out if my boat can handle the weight? Looking at the specs below… It says max passengers capacity is 465lbs, but with everything (people, motor, etc.) 915lbs. So is that 915 minus 465 (people): 450lbs total left for everything else, equipment etc.? Is that right?

Specs:
MAXIMUM CAPACITIES
4 PERSONS OR 465 LBS
915 LBS PERSONS, MOTOR, GEAR 35.0 H.P. MOTOR
THIS BOAT COMPLIES WITH U.S. COAST GUARD

Thanks in advance!

 

[racerone]

A 4 stroke Suzuki 25 HP lists at 163 lbs.----With electric start and power trim / tilt.----Yamaha is listed at even less weight.-----If money is no object, it is the best path forward.

 

[briangcc]

I'd find out what your current motor weighs and then compare with your options for re-power. The new motor may cause the boat to sit lower in the water, depending on the difference.

I know when I went from a 120 HP Force (2 stroke) to a 115 HP Honda (4 stroke) the difference was about 180lbs which cause the boat to sit a good inch lower in the water.

 

[airshot]

Normally folks use the max capacity, less the motor weight, less equipment weight then what ever is left is for people. Motor and equipment weights are fairly constant, but people and there personal items are what varies. If you have a 300# passenger one time then a 125# passenger the next time, you need to adjust...

 

[airshot]

Hello all. I have a SeaNymph 1991 with an Evinrude 15hp. I’m thinking of upgrading it to get away from a 2 stroke engine and just more power. It’s rated to go up to 35hp, but these days outboards are over 215lbs. How do I find out if my boat can handle the weight? Looking at the specs below… It says max passengers capacity is 465lbs, but with everything (people, motor, etc.) 915lbs. So is that 915 minus 465 (people): 450lbs total left for everything else, equipment etc.? Is that right?

Specs:
MAXIMUM CAPACITIES
4 PERSONS OR 465 LBS
915 LBS PERSONS, MOTOR, GEAR 35.0 H.P. MOTOR
THIS BOAT COMPLIES WITH U.S. COAST GUARD

Thanks in advance!

Sounds like you have a tiller steer....so yes the weight of the motor along with the driver at the stern can make a difference. Some folks just add enough weight at the stern to simulate the extra weight of the motor and go for a test ride before making their purchase. Weight can also be moved or added forward to counterbalance if needed..

 

[sailorb12]

Thank you all. Yeah… That’s what I was concerned about is the tilt as well. I was looking at the specs below for the river. My 15hp is a light weight. I’ve seen 14’ boats on YouTube with big motors and the transom is the same size. I don’t really have a way to try it out first before buying it. Hmmm… What to do, what to do….

• Engine Type: Yamaha Jet Four Stroke
• Horsepower: 30hp Jet Drive
• Cylinders: 3 cyl
• Shaft Length: 20" Long
• Steering: Tiller
• Starter: Electric
• Weight: 227 lbs
• Alternator Output: 16 amp
• Degree of Tilt: 65°
• Degree of Trim: -4° through + 16°
• Full Throttle Range: 5000 - 6000 rpm
• Displacement: 747cc
• Fuel Induction System: Electronic Fuel Injection (EFI)
• Warranty: Yamaha 2-Year Warranty.

 

[sailorb12]

Sounds like you have a tiller steer....so yes the weight of the motor along with the driver at the stern can make a difference. Some folks just add enough weight at the stern to simulate the extra weight of the motor and go for a test ride before making their purchase. Weight can also be moved or added forward to counterbalance if needed..

Great idea! “…add enough weight at the stern to simulate the extra weight of the motor…”
Thanks!

 

[sailorb12]

Or settle with a Merc 30hp 4 stroke 145lbs/65.7kg.

 

[airshot]

Great idea! “…add enough weight at the stern to simulate the extra weight of the motor…”
Thanks!

Unless you gave a way of hanging that weight off the stern, better use a higher weight. Remember the motor hangs over the stern, where as extra weight will be inside the stern so better add on some extra for your test. With the boat capacity shown, I rethink you will be fine, however you will need to move things around or add weight forward to get a balance, especially if going solo.....

 

[sailorb12]

Unless you gave a way of hanging that weight off the stern, better use a higher weight. Remember the motor hangs over the stern, where as extra weight will be inside the stern so better add on some extra for your test. With the boat capacity shown, I rethink you will be fine, however you will need to move things around or add weight forward to get a balance, especially if going solo.....

Yeah, totally makes sense. Thanks!
Wow, those jet motors are a hot item. Yamaha is out and the Mercs are the 15” shaft only and jumps up to 60hp 20” shaft.

 

[sailorb12]

A 4 stroke Suzuki 25 HP lists at 163 lbs.----With electric start and power trim / tilt.----Yamaha is listed at even less weight.-----If money is no object, it is the best path forward.

Thanks. I’m assuming those are regular prop motors, yes?

 

[racerone]

Props are more efficient.-----EXAMPLE----A 150 HP outboard powerhead is rated as 105 HP equivalent power from the jet.----About 40 / 45 HP is wasted in the jet unit.-----You would need a 45 HP outboard to get 30 useful HP from a jet.----Are you going to an efficient 4 stroke and then wasting that advantage in the jet ?

 

[sailorb12]

Props are more efficient.-----EXAMPLE----A 150 HP outboard powerhead is rated as 105 HP equivalent power from the jet.----About 40 / 45 HP is wasted in the jet unit.-----You would need a 45 HP outboard to get 30 useful HP from a jet.----Are you going to an efficient 4 stroke and then wasting that advantage in the jet ?

Yeah… It’s one of those things… I can’t have everything that I want. Both have their pros and cons.

I’m not completely sold yet. But the short answer why I’m leaning towards the jet for its intended use fishing and on the river: They have a shallow draft to navigate unfortunately on shallow waters when they come up without damaging my equipment. Other than its speed, reliability, maneuverability, it has fewer moving parts than prop boats, which require less maintenance and are less likely to break down. Since it doesn’t have a propeller that can become tangled in weeds or debris, which can cause a prop boat to become disabled. Etc. etc… Granted it’s less fuel efficiency, on the river I typically go up and drift down. -And this will still get me from point A to point B. Same thing on the lakes, I get to where i want to go, park it and use either my front of back trolling motor to putter along if needed.

I doubt I’ll really need it for other water activities like to pull tubes or water skiers. It’s mainly to get from point A to B and chill.

I can’t have everything I want in a motor, it’s not the best, but I’m willing to compromise.

But we’ll see…

Thanks.

 

[sailorb12]

Yeah… It’s one of those things… I can’t have everything that I want. Both have their pros and cons.

I’m not completely sold yet. But the short answer why I’m leaning towards the jet for its intended use fishing and on the river: They have a shallow draft to navigate unfortunately on shallow waters when they come up without damaging my equipment. Other than its speed, reliability, maneuverability, it has fewer moving parts than prop boats, which require less maintenance and are less likely to break down. Since it doesn’t have a propeller that can become tangled in weeds or debris, which can cause a prop boat to become disabled. Etc. etc… Granted it’s less fuel efficiency, on the river I typically go up and drift down. -And this will still get me from point A to point B. Same thing on the lakes, I get to where i want to go, park it and use either my front of back trolling motor to putter along if needed.

I doubt I’ll really need it for other water activities like to pull tubes or water skiers. It’s mainly to get from point A to B and chill.

I can’t have everything I want in a motor, it’s not the best, but I’m willing to compromise.

But we’ll see…

Thanks.

Oh the one Yamaha I read online was 40/30: 40hp motor, 30hp thrust jet motor.

 

[sailorb12]

Hello all. I have a SeaNymph 1991 with an Evinrude 15hp. I’m thinking of upgrading it to get away from a 2 stroke engine and just more power. It’s rated to go up to 35hp, but these days outboards are over 215lbs. How do I find out if my boat can handle the weight? Looking at the specs below… It says max passengers capacity is 465lbs, but with everything (people, motor, etc.) 915lbs. So is that 915 minus 465 (people): 450lbs total left for everything else, equipment etc.? Is that right?

Specs:
MAXIMUM CAPACITIES
4 PERSONS OR 465 LBS
915 LBS PERSONS, MOTOR, GEAR 35.0 H.P. MOTOR
THIS BOAT COMPLIES WITH U.S. COAST GUARD

Thanks in advance!

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