Underpowered?

[SeaNymph Man]

I have a 1973 Sea Nymph 14R 'Big Water' boat that is rated for 25 HP maximum. She came with a 9.5 HP Johnson when I bought her back in
March. I finally had a chance to try her out this week. I had the trim set
right,three blade prop that came with the motor on the motor. Two anchors on board fore and aft(actually moved the aft anchor forward to balance weight as much as possible)6 gal. fuel tank and just myself in the boat.
At W.O.T.,this little 9.5 Johnson still could not get the boat on plane,...
and that was even with the wind to my back if that has anything to do with it. The bowl rises and the boat just squats the whole time. Also,she burned a 1/4 tank of gas in less than two hours,...that's right,...TWO HOURS! I feel that I am underpowered here. What do you think?

 

[Sandhammaren05]

Re: Underpowered?

Insufficient info provided. How heavy is the boat? Prop pitch? Is the motor reving up to 5500-6000 RPM? Model nr. or year of the 9.9? Will it plane off if another passenger sits in the front?

I have a 1973 Sea Nymph 14R 'Big Water' boat that is rated for 25 HP maximum. She came with a 9.5 HP Johnson when I bought her back in
March. I finally had a chance to try her out this week. I had the trim set
right,three blade prop that came with the motor on the motor. Two anchors on board fore and aft(actually moved the aft anchor forward to balance weight as much as possible)6 gal. fuel tank and just myself in the boat.
At W.O.T.,this little 9.5 Johnson still could not get the boat on plane,...
and that was even with the wind to my back if that has anything to do with it. The bowl rises and the boat just squats the whole time. Also,she burned a 1/4 tank of gas in less than two hours,...that's right,...TWO HOURS! I feel that I am underpowered here. What do you think?

 

[tashasdaddy]

Re: Underpowered?

9.9 on a 25hp rated boat is about 1/2 the power, to get reasonable performance. the rule of thumb for minimum power is 70% of the rated power of the boat. which would be an 18 hp for minimum reasonable performance. yes, you are way underpowered.

 

[metriccrescentwrench]

Re: Underpowered?

According to this link that boat weighs 165 pounds.

http://www.iboats.com/Sea_Nymph_Boats__14R_Big_Water__1973/bp/63b73967r0

IMHO, anything less than the maximum rated HP is underpowered, but that's just me.

We had a 14' boat kinda sorta similar to that when I was a kid (and it was rated for 25 HP). My dad had an old '58 7.5 hp Johnson that had sat in our basement forever, so that's what we used on the boat. It didn't have any trouble getting on plane, even with 3 people in it. I'm wondering if maybe the engine still isn't trimmed properly, or else you've got an engine issue.

 

[crxess]

Re: Underpowered?

one for sale here with 9.9:
http://www.boats.com/listing/dealer...inesite&currencyid=100&style=dw&task=preowned

I'd be more concerned about proper motor operation,trim, prop at this time.

Have you checked for spun hub? If the prop is slipping under load it will never reach plane.

My boat is 165 pounds empty and only rated for a 7.5hp

 

[wbeaton]

Re: Underpowered?

I have several 1950's 7.5 hp motors and have yet to see one plane either my 12' or 14' open hull aluminum boats with two people.

Your 14' sounds much like my Springbok rated for 28 hp. I've run 15, 20, 25 and 30 hp motors on it and I can tell you that a 9.5 hp would never work on mine. Even the 15 hp wasn't enough with two guys.

However, my boat is very heavy due to the full floor,and gear. If yours is just an open utility then the 9.5 hp sould do fine. Still a little under powered, but fine. Take a look at the coils of your 9.5 hp and see if they are cracked, sweaty or discoloured. If they are they are bad and must be replaced. Those old coils are notorious for failure. Don't trust a spark tester. They may spark just fine on the tester, but fail under load.

 

[SeaNymph Man]

Re: Underpowered?

9.9 on a 25hp rated boat is about 1/2 the power, to get reasonable performance. the rule of thumb for minimum power is 70% of the rated power of the boat. which would be an 18 hp for minimum reasonable performance. yes, you are way underpowered.

I thought so,...but just can't seem to convince my buddies on a fishing site I belong to that I am indeed underpowered. The motor is actually a 9.5 HP,...not 9.9 HP. Still this thing,as you say,is way underpowered with that
9.5 HP Johnson. The motor runs fine otherwise. Johnsons are good motors and so is this one,...her only fault is that she is too small in the power dept.
for my boat. I need at least an 18 HP motor for reasonable performance as
you have stated,Tashasdaddy! The search is on for a bigger 'Rude or Johnny
motor. I may offer my 9.5 Johnson to any outboard motor collector who may
be interested in such a motor. Keep in mind that my motor is a 1970 model.

 

[tashasdaddy]

Re: Underpowered?

that still is a good motor, the sell quiet easily.

 

[SeaNymph Man]

Re: Underpowered?

I have several 1950's 7.5 hp motors and have yet to see one plane either my 12' or 14' open hull aluminum boats with two people.

Your 14' sounds much like my Springbok rated for 28 hp. I've run 15, 20, 25 and 30 hp motors on it and I can tell you that a 9.5 hp would never work on mine. Even the 15 hp wasn't enough with two guys.

However, my boat is very heavy due to the full floor,and gear. If yours is just an open utility then the 9.5 hp sould do fine. Still a little under powered, but fine. Take a look at the coils of your 9.5 hp and see if they are cracked, sweaty or discoloured. If they are they are bad and must be replaced. Those old coils are notorious for failure. Don't trust a spark tester. They may spark just fine on the tester, but fail under load.

Yes,it is an open utility-v bottom boat,...but it is a heavier duty boat than the Lund A-14 I used to have. I had a 15 HP Merc on that boat and it had no problem getting it up on plane,...but if that Merc was on my current boat,it
would probably suffer the same problem my 9.5 Johnson is,but maybe not as bad. I don't feel a 15 would be enough,either. As Tashasdaddy stated,I should have at least 70% of rated power minimum on my boat for reasonable performance,...which would be 18 HP. I would have to agree with both of you
that my rig is underpowered. I would say that if I could find a 1975 or later 20 HP Evinrude or Johnson motor,my boat would perform far better and may even use less fuel since it would not have to work as hard as that little 9.5
Johnson.

 

[tashasdaddy]

Re: Underpowered?

i agree 100%, if you even find a good deal on a 25.

this is a 14 ft Lonestar, 1955 15 hp, stick steering, with 2 - 200lb people, it struggled. it sort of plowed.

 

[iwombat]

Re: Underpowered?

Back in the day, I ran a 9.9 on the very same boat. It would get up on plane w/ two in the boat just barely and then cruise along pretty nicely. I think you'll be much happier with a 15 or 18 as previously mentioned.

 

[CATransplant]

Re: Underpowered?

Look for a 25 hp around 1970. Lightweight and great. I almost bought one here in the twin cities last week. It was selling for $300 with a nice tank. According to the seller it ran perfectly. It was gone after being on Craig's List for about three hours.

 

[kenmyfam]

Re: Underpowered?

Underpowered....Yes.
Get to at least three quarters of the max HP.

 

[Huron Angler]

Re: Underpowered?

I've got a friend who owns a 14' Cadillac Riviera aluminum boat that planes out very well with a 1972 Johnson 25hp longshaft. Speed is around 15-20mph ballpark. Maybe more with a shortshaft?

 

[quist11]

Re: Underpowered?

Looking at your pic's that shaft on your motor is way to long and never will plain - it will try to push the back of the boat down and the motor will be in overload ......

Trust me i've had the same problem ....

 

[krogie]

Re: Underpowered?

I dont think those pics are of seanymphs boat , i belive it is Tashasdaddys. but I would have to agree that even if the motor needs some work and it is repaired and runs like new it may be underpowered for your needs and for future equipment you may be hauling.

 

[wbeaton]

Re: Underpowered?

Looking at your pic's that shaft on your motor is way to long and never will plain - it will try to push the back of the boat down and the motor will be in overload ......

Trust me i've had the same problem ....

Ha! That's called paralax error. You can't judge the shaft length based on that photo. The motor is suited to the boat in the photo.

A long shaft motor would create drag not cause a boat to plow. Improper trim will cause it to plow.

 

[Rick.]

Re: Underpowered?

I don't have a lot of experience regarding boat set up and such. Just wanted to comment about the fuel consumption remark. I have noticed that my 9.5 uses up fuel much faster than my 9.9 and my15HP Evinrudes. I'm not sure why but I chalked it up to the lower compression of the 9.5 ( right at 60 per cylinder). Is this others experiance as well or is there a reason for the higher consumption. I'm not complaining as I know how much the bigger engines use. Rick.

 

[jasper60103]

Re: Underpowered?

OP mentioned he was squatting, so I thought I would add some trim set guidelines...