Submarining Whiplash!

[T.C.]

I still think the boat will run it's best at the recomended CG, also the last fuel race I went to they gave those boats a pretty good toss to get them up on plane.
If you move the CG back the boat will run wet, it may also want to dart or hunt in the corners?
JMHO T.C.

[Jeepers]

I still think the boat will run it's best at the recomended CG, also the last fuel race I went to they gave those boats a pretty good toss to get them up on plane.
If you move the CG back the boat will run wet, it may also want to dart or hunt in the corners?
JMHO T.C.

If you fall off plane during a race how do you expect to get going again, with that much weight in the nose?
Not all boats run the same even if built by the same builder.

you do know that recommended CG is a starting point but not always accurate. the faster you go the CG is going to change.

[Jeepers]

My UL-1 would submarine VERY easily if too much lipo weight was added up front.

Yep a club members UL1 here had to be hand tossed all the time we ended up changing the strut angle to compensate.

[T.C.]

Can/would you explain how the CG changes as the boat goes faster?
I would think if it was a fuel or gas boat the CG may change by using up the fuel.
But I dont understand how an electric boat CG would change just because it's going fast?
Unless there is something inside it that moves as it's running, and I dont know what that is?
I'm sure I'm missing something.
T.C.

[highndry]

Take the weight out and adjust the strut..!!!

[highndry]

Every boat is different..bring it over..we'll fix it

[highndry]

CG is a moving target

[Scott T]

Sailr, where is your CG, and what is the overall boat weight? Even though the set up is the same, is it the same weight as the others in your club?

Also check all the under surfaces for smoothness. Little paint imperfections can cause dramas, so even check the bits that will be out of the water when on the plane.

My Whip subs if I don't give it full throttle on launch, but it handles brilliantly in race conditions, so I live with it.

[T.C.]

I noticed that during the build of your boat there were some sponson mod's done.
I posted asking the builder why they were done, he said he didn't know, just that others had ask for the same mod's.
Could it be this sponson mod is causing your problem?
Do the other Whip's you spoke of have the sponson mod's like yours?
Just a thought.....................
T.C.

[cybercrxt]

Jim, Bet I know what is causing the problem. (For those that don't know, I built his boat, and Herber's whip). You know how you had me add that ply to the front of the center formers, well, that added a big blunt front to the boat. A blunt front like that, will plow the water to the top of the boat at low speeds, and once the water starts going over the front, its not gonna stop. I think that, combined with to much weight in the nose, is your problem. Here is a pic to compare with everyone. Mike

[teach]

Good thought! Could he taper the nose up at this point? Maybe add a small piece of balsa type wood to test that theory?

[sailr]

One of the other whips has the same mod....built by the same builder. His boat runs great....no problems. So I don't think the mod is causing the problem.

I noticed that during the build of your boat there were some sponson mod's done.
I posted asking the builder why they were done, he said he didn't know, just that others had ask for the same mod's.
Could it be this sponson mod is causing your problem?
Do the other Whip's you spoke of have the sponson mod's like yours?
Just a thought.....................
T.C.

[sailr]

Hmmm, interesting thought Mike. Rather than sanding that back down, I could add a triangle piece to that front area you mention to 'skinny' that spot down. Do you think that would work?

Jim, Bet I know what is causing the problem. (For those that don't know, I built his boat, and Herber's whip). You know how you had me add that ply to the front of the center formers, well, that added a big blunt front to the boat. A blunt front like that, will plow the water to the top of the boat at low speeds, and once the water starts going over the front, its not gonna stop. I think that, combined with to much weight in the nose, is your problem. Here is a pic to compare with everyone. Mike

[D&D]

First of all, nice boat. I really like the look of this boat.

Youstated that your boat is setup exaxtly like other boats in your club, and they you say "Any idea about the submarining problem? Do I need a bigger prop to pop it up or what? I'm using a detongued 642. One of the other guys is using and M545." Are you using exactly the same stock prop as the other members in your club?

Props can make a big difference in the attitude of the boat. I suggest borrowing a prop and see what happens to your boat.

[sailr]

Yes, I understand that. As I said, I'm using a detongued X642. So therefore, it is not a stock prop. One of the other members, whose whiplash is the fastest of the bunch, uses the same prop.

First of all, nice boat. I really like the look of this boat.

Youstated that your boat is setup exaxtly like other boats in your club, and they you say "Any idea about the submarining problem? Do I need a bigger prop to pop it up or what? I'm using a detongued 642. One of the other guys is using and M545." Are you using exactly the same stock prop as the other members in your club?

Props can make a big difference in the attitude of the boat. I suggest borrowing a prop and see what happens to your boat.