Skiing Behind Outboard Motors

[Nickman0017]

I’m in the process of repowering my 1965 whaler. The family and I use it for slalom skiing (non competitive) and barefooting. I’m looking at the 115hp Mercury Pro XS.  Does anyone have experience with this and know if I should be buying the command thrust (CT) version? I’m about 220lbs so need some power to get me out of the water on a slalom, but don’t want to sacrifice much top end for barefooting. 
 

Any help would be appreciated!

[skibrain]

You are probably on the wrong forum for input on outboard-powered recreational skiing. I have more questions than answers. 

• What outboard hp and prop pitch are you running currently?  Is it adequate?

• What length boat and what is the max hp rating for that hull?

• Another outboard or Whaler-specific form could walk you through WOT rpm / speed vs hole-shot scenarios. https://continuouswave.com/forum/viewforum.php?f=7&sid=569c13a6e5b2c8cb9923b4a5dbafe9a4. Is a whaler forum.

• My hunch is that for snappy hole shot, you’d want 17” pitch. Giving you a WOT speed 38-42 mph. Might need to watch over-rev if no load. 19” pitch is better all around, but might struggle with slalom start out of hole but run 40-45 mph.

• if your hull will handle it, buy a larger cc 150 hp.

 

[Nickman0017]

Thanks for the response. I have a 115hp Tower of Power on it now, but it’s a +40 year old 2-stroke and now has some mechanical issues that cant be fixed. Unfortunately 115hp is the max I can go on my 17ft hull.  That merc 115 pro xs Im thinking of replacing it with seems to be the best power/weight ratio 4 stroke on the market…. Just not sure if a command thrust gearbox is better for a skier or not. 
Not sure if there is a forum that is directly applicable to the topic. Most people don't use their vintage whalers like we do, I figured I’d pose the q to this forum to get the pov of any skiers who may have any thoughts on the topic. 

[skibrain]

I sent you a PM. Check out the forum I linked above. 

[03RLXi]

I can't help a lot as not familiar with your hull but I do occassionally ski behind boats similar to this photo, and due to that I'm mighty surprised your existing 115hp is enough for barefooting!!!!! How do you start? Step of a ski, or sit on a kneeboard?

The boats I ski behind are 15-19' and have 90 - 200hp. Both 2 and 4 strokes. The 90hp are really marginal, even to get up on slalom ski. Hold perfect posture, say hit it, hold on, hold, hold, hold then finally get up planing. From my experience 130 to 150hp seem the sweet spot on necessary power and low weight to minimise wake. 

[6balls]

We had a 115 merc on a '72 Switzer that was 13.5.  Hole shot was awful, top speed was fine.  It was rated for 115 but 140 had same CC's so we got an evinrude 140 and put 115 stickers on it.  Solved.  Later had a bigger switzer with a 175 evinrude, then two ski centurions with Yamaha 200 and 225.  

I would dodge the 4 stroke weight and find a nice, used, fuel injected, oil injected 2 stroke.  The Yamahas were great, I've heard great things about Evinrude E-tecs.  

Merc has never been known for hole shot torque, tho I don't know about the 4-strokes

[BraceMaker]

I'm not sure if I'd do the command thrust version, any chance you can physically lay eyes on the 115 version near you?  I've only been around fairly small whalers but does yours have the same W hull configuration?  In which case the CT engines might sit pretty exposed. 

I probably would do it so long as it looked OK hung on the boat.

[ReallyGottaSki]

I concur, a small light BW with lots of surface area, doesn't need th elarger gearcase and steeper ratios. Larger gearcase disturbs the water more. Barefooters can tell the difference between a merc 200 and yama 200.    prop down to run a little high on rpm when solo, then should be good when loaded or skiing. Stay 2s if you can, but i think you chose well, as a tower of power is about 310# so you are adding 50ish pounds to the stern, better then i presumed

[ReallyGottaSki]

heh, after more research, i'm less put off by the CT, its the 150 gearcase and only another 5#.    

[Nickman0017]

Oh interesting. Yes it is that same W hull configuration. 
 

ReallyGottaSki, so you think either world work / think 1 would be more preferable over the other?

[FullFlavorPike]

Like 6balls said, a two stroke repower would be the way to go if you can.
 

 

The discontinued etec is going to be a good bet for a lightweight high output repower. The HO models apparently push a lot more power than they are rated at. “Hot” motors sort of like your old tower of power. 

[jpwhit]

The etec was a great motor, but keep in mind that Evinrude has shutdown and while technically they worked out a deal with Mercury to provide support, it's not likely to be particularly good support.  

[FullFlavorPike]

1 hour ago, jpwhit said:

The etec was a great motor, but keep in mind that Evinrude has shutdown and while technically they worked out a deal with Mercury to provide support, it's not likely to be particularly good support.  

I had that thought too but then I figured if OP wants to turn his vintage whaler into a ski boat he sounds like the kind of guy who doesn’t let a lack of factory support hold him back 😂