Great video on youtube...

Designs for inboard or outboard power

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2quick
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Great video on youtube...

Post by 2quick » Thu Sep 06, 2007 5:45 pm

Guys, go have a look at "hydroplane test #1" on youtube.com. This guy built a hydro and while he is buzzing across the lake his outboard breaks off of the transom!

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Dave Grason
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Post by Dave Grason » Thu Sep 06, 2007 7:36 pm

That's unbelievable!! Here's the link folks:

http://www.youtube.com/watch?v=z8cE4YLIzMA

It looks like each time they wanted to really give it some throttle, the motor would start these weird side to side gyrations. On the vidio around the 3:00 minute mark, this prob showed up. You would have thought they would not have wanted to push their luck.
Isn't it amazing!! The person that never has the fortitude to pursue his own dreams, will be the first to try and discourage you from pursuing yours.

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Bill Edmundson
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Post by Bill Edmundson » Thu Sep 06, 2007 8:28 pm

Watch the motor at idle. It's dancing then. Looks trimmed to high, too.

Too nice of a boat to not do your home work. I could not tell if the transom broke out or the engine pulled out. The boat didn't seem to sit down. The engine was being held up by something. I'd guess the engine was loose!

:shock: :roll:

Bill
Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
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FDMSIV
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Post by FDMSIV » Thu Sep 06, 2007 8:42 pm

The boat never really gets up on a good plane

chappo1970
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Post by chappo1970 » Thu Sep 06, 2007 9:09 pm

Doesn't look like the motor was bolted on thru the transom. Althought the engine must have been teathered to boat as in the last shot it is on its side right at the back of the transom. Very lucky the motor didn't join them in the boat.
"There is nothing that duct tape cannot fix."

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Caber-Feidh
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Post by Caber-Feidh » Thu Sep 06, 2007 11:22 pm

I think Bill is right, they are loading the transom too much with that trim. You would have thought that scary porpoising would have been a hint something was amiss.

He has a second clip posted. (after the repair). They have the motor trimmed to the opposite extreme in it. Still looks like the bow is light even with that that merc 115 trimmed way in. It's an X-1, max 100 Hp rated (although I can't figure out where they came up with that number, the transom is way too narrow for the weight.)

Any guess as to what their first words were as the motor was taking a dive? (I don't think Dave wouldn't be very happy if you posted them :wink: )

Gustav

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narduccimarine
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Post by narduccimarine » Fri Sep 07, 2007 5:42 am

If you watch the front sponsons, they never touch the water. The boat is planing on the aft surface where it should never be touching. That boat should be riding on the front sponsons and the bottom half of the prop.
I think they needed a prop with much more lift.
What a disaster.
Bob
I just don't understand, I cut that plank twice and its still too short
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Amm
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Post by Amm » Fri Sep 07, 2007 7:58 am

Biggest problem(beside not bolting the engine) looks to be the weight distribution. 2 People, the boat was probably meant for one and a huge engine. Makes for a rear heavy hydroplane. Tunnel Mite would have been less sensitive to improper weight distribution.

2quick
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I...

Post by 2quick » Fri Sep 07, 2007 3:45 pm

emailed him and asked for all of the info, including the fix. I'll let ya's know what he tells me. The steering cables are what held the motor on. Amazing...

2quick
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Spoke with him...

Post by 2quick » Fri Sep 07, 2007 4:46 pm

He emailed me back and says he only had it clamped on- no bolts. Since, it has been bolted. He also was telling me about a tracking problem. I Told him about this website and what a wealth of information can be found in this forum. Maybe he'll chime in...

mattking
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im the guy in the boat

Post by mattking » Fri Sep 07, 2007 4:57 pm

i guess you've all seen it, and i guess you've realized i need some help. the original plans of this boat where the x-1 plans, but me and my father changed the front of it completely to something we liked more. the plans said the transom could hold 100 hp, we have a 90 on it, sitting up high so the prop and plate above is just under water. its accelerating really well right now, but the top end speeds are only around 40 mph. I also can't seem to get the boat on the sponsons, and I am not sure how to go at getting them down. I am planning on increasing the prop pitch. I havn't even played around with trim yet since the front gets squirrelly on me. Should I put a fin up front? Or potentially something in the water from the front to back along the keel? Your help would be greatly appreciated. Thanks!

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BruceDow
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Post by BruceDow » Fri Sep 07, 2007 5:16 pm

Matt:

Welcome to the forum. You will find the folks here are very knowledgable and very supportive.

Good luck with the "tuning".
Bruce.

~~ Do what you love, and love what you do. ~~
~~ To me - only my boat is not yet perfect. Everybody else's is to be admired for I know the path they have walked (Dave Lott, 2010) ~~
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Dave Grason
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Post by Dave Grason » Mon Sep 10, 2007 9:50 am

narduccimarine wrote: .....That boat should be riding on the front sponsons and the bottom half of the prop......
Now THIS I didn't know, but it does make sense.

So how do you get a "higher lift prop?" Does it need to be surface piercing?

Anyway, welcome Matt to the forum and I really hope someone here can help on this.
Isn't it amazing!! The person that never has the fortitude to pursue his own dreams, will be the first to try and discourage you from pursuing yours.

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narduccimarine
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Post by narduccimarine » Mon Sep 10, 2007 10:20 am

Dave,
This boat appears to be a 3 point hydro, which should touch the water at 3 points, the tips of each sponson, and the hub and half of the prop.
Although I dont claim to be an expert on these things, I have run quite a few R/C hydros at speeds up to 80 MPH. The set up is very similar to a full scale boat. The prop lift is described below and every hydro might have a different requirement for lift. Having a second person aboard on such a small boat surely has an effect !
"Stern lift of a prop is affected by the rake of the prop blades. A highly raked prop produces a very narrow cone of thrust, which is directed almost straight back, and which leverages the bow up. A stern lifter has a much broader thrust cone directed rearward, with a greater portion of that thrust directed outwards in all directions, and also in a downward vector, helping to lift the stern. The equal upward thrust component of the cone is not very effective because it just produces a rooster tail in the middle of the wake since the prop is running fairly close to the surface if the motor is installed correctly. "
Bob
I just don't understand, I cut that plank twice and its still too short
http://www.narduccimarine.freehosting.net

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Caber-Feidh
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Post by Caber-Feidh » Mon Sep 10, 2007 10:23 am

A 4-blade will add substantially to the stern-lift. Although top speed will suffer a bit, the slippage will be reduced.

What prop are you running right now? Any guess of WOT Rpm? To hit 70Mph it would take 33" of pitch. (realistic speeds of 60+ should be possible with that setup.) A minimum starting point should be in the 28" pitch range.

Recommend Piranha propeller, they will swap undamaged blades with you to find the right setup.

Like your boat, allot of potential there.

(I bet your current prop is about 19" pitch)

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