Take off Thrust

[Bob Calliham]

Looking for suggestions for more take off thrust from a 150 Four Stroke pushing a Chapparal 191; trying to get a 200lb slalom skier up easily.

[TownsendsFJR1300]

What's your WOT RPM'S?

If your taching out at 6,000, that engine should yank your skier out of the water pretty quick..

IE, if the engine is running properly, it'll run best if propped for 6,000 RPM's. 5-6K is spec BUT at 5k, the engine is a dog (been there, done that)..

[Bob Calliham]

What's your WOT RPM'S?

If your taching out at 6,000, that engine should yank your skier out of the water pretty quick..

IE, if the engine is running properly, it'll run best if propped for 6,000 RPM's. 5-6K is spec BUT at 5k, the engine is a dog (been there, done that)..

Thanks; appreciate that insight.

[DennisG01]

I've slalomed behind a 19' Sea Ray with a 150HP. The thing literally leaps out of the hole and has no problem pulling a slalom skier. I would think your setup should be similar? In addition to what was mentioned, are you sure you are trimming down all the way?

If you really need to, adding something Smart Tabs would make a huge difference in hole shot. I've used (and installed) them on multiple small boats and they are great. Installing a full-on hydraulic setup is fine, but costly and overkill. The Smart Tabs are much less expensive and faster to install - about an hour if you're comfortable drilling holes below the waterline.

Putting on a different prop for when you're skiing is, of course, an option. Drop a couple inches in pitch and maybe use a 4-blade. You'll just have to manage your throttle so you don't over-rev, though. But the Tabs will allow you to keep the same prop... and will also help to keep the bow from bouncing around in a chop, too.

[pstephens46]

I've slalomed behind a 19' Sea Ray with a 150HP. The thing literally leaps out of the hole and has no problem pulling a slalom skier. I would think your setup should be similar? In addition to what was mentioned, are you sure you are trimming down all the way?

If you really need to, adding something Smart Tabs would make a huge difference in hole shot. I've used (and installed) them on multiple small boats and they are great. Installing a full-on hydraulic setup is fine, but costly and overkill. The Smart Tabs are much less expensive and faster to install - about an hour if you're comfortable drilling holes below the waterline.

Putting on a different prop for when you're skiing is, of course, an option. Drop a couple inches in pitch and maybe use a 4-blade. You'll just have to manage your throttle so you don't over-rev, though. But the Tabs will allow you to keep the same prop... and will also help to keep the bow from bouncing around in a chop, too.

You skied behind an F150 Yamaha? I wouldn’t. If the boat doesn’t pop you right up, it really sucks. If I had to pull a 200lb slalom guy up and out with my F150, I would try to find a good 4 blade.

Give me a boat with a 350 V8 inboard with a nice big bronze prop and I’ll be happy. Inhaling water and being beat to death is no fun!

[DennisG01]

You skied behind an F150 Yamaha? I wouldn’t. If the boat doesn’t pop you right up, it really sucks. If I had to pull a 200lb slalom guy up and out with my F150, I would try to find a good 4 blade.

Give me a boat with a 350 V8 inboard with a nice big bronze prop and I’ll be happy. Inhaling water and being beat to death is no fun!

It was a Merc, but yes. I've slalomed behind an 18-footer Sea Ray with a little 4-banger I/O... all the way up to a 28' cruiser. And, of course, behind a 350 V8 inboard with a nice big bronze prop. But every time I ski behind that Mastercraft, I want to do it less and less behind I'O/s or O/B's... MasterCraft/Nautique/Moomba/etc... those are like cheatin'!!!!

Crossing that wake on the cruiser... better have good knees!

[BQUICK]

Vented prop helps holeshot

[zenoahphobic]

The answers given demonstrates that this is a difficult topic, as there is a boat and a water skier wanting to get up on the plane at the same time.

A vented prop has the opposite affect to a four bladed prop. The former has inbuilt slip and the latter has more grip.

The WOT question is irrelevant when it tends to refer to revolutions limit at maximum speed.

A 150 horsepower should be able to deliver a relatively quick start for a competent 200 slalom skier it is just a question of using a lower pitch propeller.
A happy medium needs to be stuck; and I would start by choosing a prop that does not see the engine screaming at the final speed the 200 pounder wants to slalom at. This would mean at that point no more than half to three quarter throttle. Two pitches down seems a consensus.

Of course WOT would be used to start with a gradual reduction in sync with the increasing speed technique carefully used by the driver.
Now that is important if the skier is a novice. Almost any adult dead weight can cause hardship to a max speed max revolution boat if they want to; the skier needs to contribute to his rise out of the water.

I have been skiing for sixty years, been there done that. At 6 3 I have been able to sustain on a single behind a 20hp,! And have found V8 act like dogs, the pathetic mercruisers on upward of 20 foot boats.
I must add that these days I make it easier to start on two and then drop one!

[boscoe99]

You skied behind an F150 Yamaha? I wouldn’t. If the boat doesn’t pop you right up, it really sucks. If I had to pull a 200lb slalom guy up and out with my F150, I would try to find a good 4 blade.

Give me a boat with a 350 V8 inboard with a nice big bronze prop and I’ll be happy. Inhaling water and being beat to death is no fun!

Times have changed. In the sixties we skied behind my dad's boat. 16' plywood with an 80 HP Mercury tower of power. Skied behind a friends boat that was 14' fiber glass with a 35 Evinrude. We did what we did and used what we had.

Maybe ite helped to teach a skier how to get up on plane with the ski along with the boat.

[99yam40]

very true.
we that learned to ski behind small outboards could not sit back and wait for the boat to just pull us up.
We had to learn to bend knees up to our chests and then step up( straighten out) to get our body up out of the water once a little forward motion was obtained to reduce the drag.
getting up on 2 and dropping one was a learning experience, and I think most everyone got it done eventually

I once made skis out of wood barrel slats.
had to sit on a regular ski to get up, and then stand up and let the large ski slide out from under me.

they were curved side to side and front to back, so there was no control of where you went.
that was a failed project that I gave up on quickly

[pstephens46]

Times have changed. In the sixties we skied behind my dad's boat. 16' plywood with an 80 HP Mercury tower of power. Skied behind a friends boat that was 14' fiber glass with a 35 Evinrude. We did what we did and used what we had.

Maybe ite helped to teach a skier how to get up on plane with the ski along with the boat.

Getting up on two skis is one thing. Getting pulled up on one is a little different. OP mentioned slalom.

[zenoahphobic]

Getting up on two skis is one thing. Getting pulled up on one is a little different. OP mentioned slalom.

The good old days when power was limited taught us to ski well.
The tightly crouching exactly central over the single ski, with the rear leg trailing or tightly in the rear binding, was an art. Timing was of essence. In a way you are using your ski, like with two skis, to deflect the water to reduce body drag and to rise quickly (but not too quickly) out of the water stream.

I think we are making assumptions about the OP's heavy skier ability and strength!
These days I want to enjoy the skiing and not the challenge of the start anymore. Even have forgone the jump start, even if it means a cold dunk sitting into the water. And I do it behind a JetSki that really doesn't have a problem with its ability to get onto the plane even with a 100kg load behind its own 350kg weight, plus another 100kg driver! That's over 50% additional payload, imagine doing that with a conventional boat.

[99yam40]

I could come up on one , while being pulled buy a 45 HP Sea king..
we pulled 2 skiers up at a time (on 2 tho)
there were people that tried to ski that just did not get how to help the boat get them up and would just get dragged until they lost their grip on the ski rope.
I have taken off from sitting on a pier and came back and sat back down on the same pier when finished skiing and never got wet before

[pstephens46]

The good old days when power was limited taught us to ski well.
The tightly crouching exactly central over the single ski, with the rear leg trailing or tightly in the rear binding, was an art. Timing was of essence. In a way you are using your ski, like with two skis, to deflect the water to reduce body drag and to rise quickly (but not too quickly) out of the water stream.

I think we are making assumptions about the OP's heavy skier ability and strength!
These days I want to enjoy the skiing and not the challenge of the start anymore. Even have forgone the jump start, even if it means a cold dunk sitting into the water. And I do it behind a JetSki that really doesn't have a problem with its ability to get onto the plane even with a 100kg load behind its own 350kg weight, plus another 100kg driver! That's over 50% additional payload, imagine doing that with a conventional boat.

Yes it can be done. Done it before.

Not or doing it again without lots of giddy up and go.

sking on two skis stinks and I am not dropping one. Kinda narrows it down. Now maybe a 300 HDPI would do the trick. I’ll drag you you guys around all day with the F150.

[99yam40]

what is it about skiing do you enjoy?
it was seeing what all we could do before wiping out.
Dad would look over at me a smile when I cut over hard to the side and catch up to the boat( almost shoulder against the water).
he would then whip the wheel in my direction for a split second causing me to hit the water and skip over the water as I came out of the ski.

to tell the truth it became boring just cutting back and forth across the wake.
you did use musels you did not normally use and got sore after a good day
I do not think I have skied in 30 or 40 years