Ski boat question.....
Here's one of the many fields I need to know more about; ski and
wakeboard tow boats.I'm writing a very short piece (surprise!) noting that a manufacturer
of tow boats has appointed a dealer in the Pacific NW. While looking
over some of their models last week I noticed that they are equipped
with ballast tanks- and I do understand the benefit of making the boat
heacy in the stern to adjust the wake for wakeboarding. I also noticed that even the smallest boats in this manufacturer's
line (about 20 feet) are all inboards, with the rudder slightly offset
from centerline. I presume the location of the rudder allows the boat
to turn circles in one direction faster than in the other? I was told that "all tournament quality tow boats are inboards". Is
there something about the function or physics of a tow boat that
precludes using an IO, or is it more of a safety and logistics issue
associated with getting the running gear under the boat away from the
skier or wakeboarder and the tow line? |
Chuck
Apr 1
|
| Chuck, the rudder is offset to facilitate the removal of the driveshaft. The boat should turn equally in either direction. Many drivers prefer to
turn to Starboard to pick up a fallen skier. (Their view is unobstructed)
With the inboard configuration you can set the desired speed and the
boat will generally maintain that speed whereas many IO's will vary
their speed considerably, especially at wakeboard speeds.
And of course the fins that are mounted on the hull directly below the
ski pylon ensure that the boat will track properly.
There are some fairly decent IO ski boats available, but the serious
skiers should be better served with an inboard.
Good luck and good boating,
Jim Chuck Gould wrote: |
Jim
Apr 4
|
| I wonder if part of the reason is tradition. I remember as a kid living on
a lake during the summer the boat used for competition skiing and ski
"shows" was an inboard powered Ski Nautique. I don't recall ever seeing an
I/O configured boat on this smallish lake ... the rest were all outboards.
In those days a "big" outboard motor was a 75 or 100 hp Merc or Evinrude and
they usually struggled to pull up one slalom skier. The Ski Nautique often
towed five or six of us with girls on our shoulders. Eisboch |
Eisboch
Apr 4
|
| Master Craft has been around for a long time also and they were always
inboards if my memory is correct. I'd guess that the inboards were
cheaper to run and had more power than the 2 stroke OBs available in
those days. |
Wayne.B
Apr 4
|
| I never noticed the tattoos on your shoulders. Hee Hee |
Jim
Apr 4
|
| Learned a few months ago that they actually did make some with
outboards. Looks like in the early 90's the Prostar and the
Barefoot were available with outboards. http://www.sdwaterski.org/boats.html sam |
Sam
Apr 4
|
| One of the boats we had was about an 18 footer with an old, 75hp (I think)
Mercury "Thunderbolt". The engine was huge. The little lake we were on was
about a mile long and maybe 3/4's of a mile wide. At WOT, that thing could make about 5-6 circuits of the lake before we'd
have to fill up the 6 gallon gas tank again. Eisboch |
RCE
Apr 4
|
| Likewise, I had heard that you have less of a wake, and since the
engine's weight is midships, you have a faster plane and more
predictable, controlable power. Plus you have a better towing power at
a low speed (wakeboard/trick ski) interesting that the rudder is still off to one side of the prop. My
old '64 Chris Craft cavalier had the rudder offset as well. supposedly
to steer better when engine was under hard throttle torque, but
backing up was horrible. it would pull only to one side. Chuck Gould wrote: |
Tim
Apr 4
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| You never sat on my shoulders. And guess what? You never will. Eisboch |
RCE
Apr 4
|
| Interesting, My '73 CC Ski Nautique's rudder isn't offset and its fairly
simple to just drop the rudder to remove the shaft. ?? UD |
capuglydan
Apr 4
|
| >there something about the function or physics of a tow boat that
>precludes using an IO, or is it more of a safety and logistics issue
>associated with getting the running gear under the boat away from the
>skier or wakeboarder and the tow line? Safety could be one issue but it could also be related to reliability
and maintenance. Conventional wisdom around here is that straight
inboards require a lot less maintenance and are consequently more
reliable in heavy service. That said, I/Os have their advantages for
operating in shallow water, trailering and ease of prop maintenance.
Also, because of their inline prop thrust, I/Os usually offer more top
end speed. Since none of those advantages are likely to be important
to a tournament tow boat, you could also argue that the additional
expense of an I/O is not worthwhile. |
Wayne.B
Apr 1
|
| All of your points are valid, but the real reason is goes back to
tournament ski boats needed to have smooth water behind the boat, and
the inboard left a much smaller footprint (ie smoother water) than an I/O. This probably isn't as important for wakeboard boats, but my guess is
most wakeboard boats also double as skiboats. |
Reginald
Apr 1
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