Enough horsepower?

[909]

People RARELY downgrade, but almost ALWAYS upgrade.

They can't fix it it themselves, and so they will lie to your face.

And you'll end up with their problems.

 

[emoney]

I wonder how this turned out? It does seem odd that someone was willing to trade "down" in HP on the same year model motor. If I was trying to moving from a higher HP to a lower one I'd at least want to make sure whatever I'm trading for is at the very least, newer. As to the OP's question about, "will I still want the 140hp"...that answer's easy; of course you will. However, if someone is willing to trade you a 110hp for a 70hp and they're both similar years and in similar condition, that's a no-brainer, regardless of if it's your dream choice or not. Because, at the end of the day, the 110hp is worth more than your 70hp is even if you end up trading again in a few weeks/months/days/whatever time frame. Also, I'm surprised that boat has a 70hp on it and I wonder if that wasn't just what someone had acccess to. I'd at the very least expect a 90hp and even that isn't enough.

 

[BrianVT]

Thanks for the continued input.
I never even got to the point of checking the other engine out. He sent some pics with the cowl off and it looked pretty rough. I think I saw some "handyman" fixes in there.
I guess I'll hold out for something closer to a 140hp. and maybe try to double-check the boat's weight between now and then.

 

[QBhoy]

Surely she will plane 3 up, if the prop is well suited ? When I was a kid…a 70hp was a big engine. Jeez…similar sized boats would pull a skier with as much and less too.

 

[BrianVT]

I suppose I should look into what prop. is, or should be, on there.

 

[jimmbo]

Surely she will plane 3 up, if the prop is well suited ? When I was a kid…a 70hp was a big engine. Jeez…similar sized boats would pull a skier with as much and less too.

When I was a teenager, I learned to Ski behind a 40hp, that included Deep Water Starts on a Slalom Ski. I wasn't a feather weight either.

 

[BrianVT]

This is a pretty heavy boat, though.

 

[QBhoy]

When I was a teenager, I learned to Ski behind a 40hp, that included Deep Water Starts on a Slalom Ski. I wasn't a feather weight either.

Exactly. My parents used to ski behind a 17ft 2 berth with a 40 Yamaha. Completely normal back then. This boat should plane with 70hp and a few onboard. Just needs propped well. No doubt more power would be better…but should do ok with a 70.

 

[BrianVT]

I appreciate the replies.
I tried looking into prop. selection but I still have no clue how that works.
Any advice on what direction to head with a new prop.?

 

[harringtondav]

Start with an online propeller selector tool. iBoats has one shown below. This will show the spline size, prop diameter and recommended blade pitch.
The rule of thumb always holds: Lower pitch = faster planing and low end towing power, but lower top speed. Higher pitch = slower planing and higher top speed.
Your prop likely has a number showing model number and diameter x pitch. If it doesn't take it to a prop shop. They can give you this info. Based on your complaint, I'd recommend you stay with the same diameter and one pitch size lower.

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[BrianVT]

Thank you. That helps.

 

[jimmbo]

However do not expect a difference in Speed of more than One or Two mph, as the Pitch changes from low to high, within a given Prop Line. More Pitch increases the Load on the Engine, and a lower WOT rpm results, and overall, little if any change to Top Speed. Changing Brands/Model of the prop throws a curve/variable into the Equation.

 

[BrianVT]

I found the prop. # and it's a 10 5/8"diameter x 11" pitch.
EzPartsWeb lists 10 5/8" diameter and 10" through 17" pitch for my engine.
Should I be thinking about buying a 10" pitch? Or a 12"?
With the 11" pitch it won't get on plane with 3 people on board and it struggles to pull someone on a tube (maybe 5 mph max.?) with 2 on board.
It will plane with 2 on board but prob. tops out @ 25mph?
My tach. and speedo. don't work. It doesn't sound like it's over-revving at top speed.

FWIW, I have a (not running) Classic 50 that has a 10 7/8"diameter x 11" pitch on it. That may have the same spline so I could try it but I don't know what difference 1/4" diameter would make.

 

[jimmbo]

How about getting a new Tachometer? Very few, and I mean, very few people can tell, by sound, what rpm an Engine is running

 

[harringtondav]

I found the prop. # and it's a 10 5/8"diameter x 11" pitch.
EzPartsWeb lists 10 5/8" diameter and 10" through 17" pitch for my engine.
Should I be thinking about buying a 10" pitch? Or a 12"?
With the 11" pitch it won't get on plane with 3 people on board and it struggles to pull someone on a tube (maybe 5 mph max.?) with 2 on board.
It will plane with 2 on board but prob. tops out @ 25mph?
My tach. and speedo. don't work. It doesn't sound like it's over-revving at top speed.

FWIW, I have a (not running) Classic 50 that has a 10 7/8"diameter x 11" pitch on it. That may have the same spline so I could try it but I don't know what difference 1/4" diameter would make.

Planing @ 25 mph and towing @ 5 mph sounds like you are hp limited for your boat and needs. Props can't increase hp, only adjust how you use it. Per your post title "Enough horsepower? ...seems no.
There are many reasons your boat is under performing vs. the many sage comments above. Waterlogged flotation foam or too much gear increases weight, hull fouling increases drag, etc.
So if your pockets are deep enough, forget about props and sell or trade your current motor and upgrade to a higher hp O/B. Up to the max rated 140 hp if you can afford it.

 

[airshot]

Check yiur boat first for waterlogged foam, otherwise your wasting money on a motor when the issue is your boat!!! Start at square one......

 

[harringtondav]

Check yiur boat first for waterlogged foam, otherwise your wasting money on a motor when the issue is your boat!!! Start at square one......

Right on. The original post brochure pics stated 1670# dry. That is w/o your O/B motor. ...maybe someone will chime in with a guess on its weight. I SWAG around 120#.
Getting a weight for your boat is simple: Unload all gear and note approx. fuel . Tow the boat to a scale and get a weight. ...ask for a re weigh, often costs less than another weigh. Launch the boat and tie it off. Re weigh the tow vehicle and trailer. The difference is the boat's weight. Figure 8 lbs/gal for any gas.
Assuming the brochure and my motor weight guess are close, your boat should weigh 1800-1900#. Much more and, per @airshot , you'll be throwing good money after bad.