Ski tow boat builders... lend me your tips and wisdom!

Designs for inboard or outboard power

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ParkerJ
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Ski tow boat builders... lend me your tips and wisdom!

Postby ParkerJ » Mon Jun 12, 2017 10:37 pm

Alright everyone... after skulking around the website... youtube and the forums, I have finally decided on the boat I think would best suit my skill, wallet and purpose: the ski tow.

I wanted my first project to be plywood based... to be an outboard... and primarily a boat we could take out on our lakes to have some fun with the family. Our first child is turning one on Thursday and I would like to have this completed by the time he is old enough to be pulled in a tube... the ski tow seems to fall under a few of these requirements.

A few questions right off the bat:

1) I am 6' 2"... my wife fairly petit. If seated in a convertible like an MG or Bimmer.... my eye balls and hair are usually the first things to get an injection of wind right to the face :lol: With this design, is there enough room for me to mess around with seat height so I am not ALWAYS in the position of having to squint whilst driving? I know this also has to do with size and height of the windscreen but I thought I would ask.

2) Most importantly... how has everyone towed their skiers and tubers? I really want to avoid using a tow bar or post or anything that strays from the classic look of these boats. How did you go about pulling people behind your boat from the transom and not have it rip out? (I am 210b)

3) For those of you who have built and take your ski tow out on the lake... how does it handle chop? Is it wide enough to plane through waves by other wakes or wind?

Mark-NJ
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Location: New Jersey

Re: Ski tow boat builders... lend me your tips and wisdom!

Postby Mark-NJ » Tue Jun 13, 2017 6:09 am

I can't answer your specific questions, as mine is now nearing completion and has yet to be launched....but if you want to see mine, there's a lot of pictures in my build thread: viewtopic.php?f=2&t=29333

For what it's worth, I built mine as a "utility"......open back, simplified seating. Like an old Thompson or Lyman.

ParkerJ
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Re: Ski tow boat builders... lend me your tips and wisdom!

Postby ParkerJ » Tue Jun 13, 2017 7:04 am

Thanks Mark, your thread is actually what sealed the deal for me! Every page, you seemed to be asking the same questions I had in my head and voila, you answered it And with pictures! :D its been bookmarked and subscribed. Its looking great! Was your open back design included in the design plans, are there a few to "choose from" or once the top decking is started, you can roam free with ideas?

PeterG
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Re: Ski tow boat builders... lend me your tips and wisdom!

Postby PeterG » Tue Jun 13, 2017 8:31 am

For towing tubes or skiers' you obviously need power like a 50hp or more for the Ski Tow. For anything over 30hp I strongly recommend installing the interior transom support/bracing structure per the plans. Mark did not install that structure, he opted for an open boat and he knew he was using a lower HP outboard that won't overstress the transom.
Period boats often used a tow harness, it consists of a rope that connects to the transom on either side of the outboard, and has a pulley/traveler tow rope connector that rides back and forth on the harness. Here is an example...

https://www.westmarine.com/buy/airhead- ... ecordNum=2

The Ski Tow is a great choice and Mark's is a great example to follow. You can look closely at Malahini projects too. They are identical to the Ski Tow in construction using the same frames and structure but the frames are spaced a little further apart to make the Malahini longer. As far as keeping the wind off your face, you can set the seat height where you want, combined with a boat windshield that works for you.
Murphy's Law: Anything that can go wrong, will go wrong.
Griffin's Law: Murphy was an optimist.

Mark-NJ
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Location: New Jersey

Re: Ski tow boat builders... lend me your tips and wisdom!

Postby Mark-NJ » Tue Jun 13, 2017 9:43 am

Parker,

My open back was NOT part of the plans....I did it this way on my own, because that's what I wanted, and knowing that I'd most likely never put more that maybe 35HP on it.

I'll know in Aug exactly how it performs with my 15HP. It will never be a "speed demon" at 15HP, but that was never my goal anyway. That said, if it's a complete dog with the 15, I'll be cruising the classifieds looking for a BigTwin or a Javelin, etc. i.e. something in the 25 - 35 range.

Let's think about this, too:

How did you go about pulling people behind your boat from the transom and not have it rip out? (I am 210b)


Imagine the transom, alone, aside from the rest of the boat. From the standpoint of the forces placed upon it, consider the transom as both the connection for the engine and the skier: short of "folding it back on itself", the transom...if thick & solid enough...will tolerate a skier no problem. If you visualize just a transom, engine & skier (i.e. "no boat"), it's easy to see that it's the integral strength of the transom alone that is the key.

By contrast, if you had an inboard engine, there's certainly a calculable amount of drag on the transom that could rip it right out, clearly making the transom's connection to keel, chine & sheer critical. But with an outboard engine mounted to the same structure from which the skier is towed, short of a failure of the transom itself, there's far, far less of an issue.

The big issue with the transom-to-"boat" connection on an outboard is with the size of the engine itself and its weight-to-moment ratio: mounting an engine that's too heavy or too much HP, and the forces on the sheer/chine/battens/keel can become stressed to the point of failure. That needs to be avoided, of course.

ParkerJ
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Re: Ski tow boat builders... lend me your tips and wisdom!

Postby ParkerJ » Tue Jun 13, 2017 9:17 pm

Thank you Mark and Peter for thoughtful replies! This is only my third post and I already feel part of a club lol.

Peter: It was definitely a toss up between the Malahini and Ski tow but length ( even a foot or two) made the ski tow a better candidate. I've noticed that different builders have included features found primarily on the malahini... in the ski tow... I.E storage behind front seats, stowage underneath and behind rear seats... so this gave me some hope in creating a combination of the two.

Mark: thank you for creating such a detailed account of your build. I will be referencing it a lot... I can appreciate the choices you made on your construction. I think it's a beautiful boat!!

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rbrandenstein
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Re: Ski tow boat builders... lend me your tips and wisdom!

Postby rbrandenstein » Wed Jun 14, 2017 8:34 am

You also asked about chop. As Peter mentioned, the Ski Tow is a shortened Malahini, (or vice versa). It does OK in light chop, but if the chop gets a little bigger you can get some pounding and wet from spray. Our lake can get pretty rough at times and you cannot cruise on plane in those conditions. I have learned to slow down and take the waves from the side, gently rolling with the punches.
If the Ski Tow has spray rails in the plans, put them on.
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Hercdrvr
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Re: Ski tow boat builders... lend me your tips and wisdom!

Postby Hercdrvr » Wed Jun 14, 2017 2:27 pm

If you plan on skiing or serious tubing it's going to take some HP. A 50 is going to leave you wanting more. If you have the build space, build the Malahini version. It costs the same and it's easier to make everything fit together, seats, hatches, fuel tank, battery, etc...why leave boat on the drawing board? Mine is actually 16'6", I snuk in another inch or so between each frame.
Bob is spot on about the ride quality in choppy water.

Just my opinions, yours will vary.
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Mark-NJ
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Re: Ski tow boat builders... lend me your tips and wisdom!

Postby Mark-NJ » Wed Jun 14, 2017 5:29 pm

Nice boat!

Is it too late to stretch my ski-tow???? :)


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