Stability Problems

Gonzo:

Yes, im referring a foil attached to the anti ventilation plate .

upload a photo,

would be nice to know if anyone had experience with these hydrofoils.

otherwise we put the trim tabs.

Thanks =)

 

Mr Efficiency:

Are we saying that the boats leans one way or the other with little or no movement in weight, from side to side.

Example,

when I am driving alone, maybe the weight of 1 gallon pail of fuel.
the stability of the boat changes.

does not strictly alone, but with the minimum impact of weight or movement tilts.

at the factory told me that the boat has a lot of V

When other people drive my boat, they feel very insecure

Thanks...

 

The spray rails are not correct in terms of placement, width, shape or a combination. If you look at the surface of the wash, you will see that the surface gets "rough" on the "low" side, and very smooth on the "high". The roughness indicates a mix of water/air, that is created when the diagonal flow over the spray rails is reattaching, thereby "encapsulating" pockets of air.

The water is not separating correctly on the "low" side and tends to reattachment, which will lower the pressure over a considerable part of the wetted surface. Typically, the boat is unstable at medium speeds, but becomes stable when speed is increased (dynamic pressure differentials becoming high enough to stimulate a stable separation process).

In order to recommend a remedy, we need to see pictures of the bottom, in addition to a few measurements of spray rail dimensions and their position. If you are lucky, the medicine may be just adding a sharp-edged aluminium profile along part of the rails, but let's see a few bottom pics first!

You should not use foils added to the outboard rig, that may well make things worse in this case.

 

Difficult to see where the strakes are, but looking at the pics their appears to be 2 each side, and it looks like the inboard one extends to the transom, but the outboard one does not, which seems the opposite of normal.

 

Quite my observation as well; question then: are there more "unusual" tweaks in the rail "design"?

 

Hello, Thanks again to all.

hopefully we are closer to finding a solution.

I got more photos for you to evaluate the design of the hull and a possible solution.

In case of the trim tabs, which I recommend to buy?

I was watching E bay, but do not know which is correct.

Thanks friends!

 

do you find something strange in the design of the boat?

 

More photos

 

Yes, there are a few things to be checked, but I will come back on these. One ting for now, though: DONT WASTE MONEY ON TRIM TABS, the problem you have is NOT related to lack of transom lift. On the contrary, if you increase lift with trim tabs, you will increase the risk for broaching, i.e. the boat is suddenly jumping off course without a chance for you to apply a correcting maneuvre.

 

i send to all you, a pdf of the boat

 

Incompetent design of spraystrip

Remove the lower spraystrip.
May be replaced with a spraystrip higher up.

js

 

The data supplied by the OP says the hull weighs 300kg. If so, I'd say she is pretty light for the type of bottom she has, which looks to be about 16/17 degrees at the transom. You'd have to think the chines would stand clear of the water at rest.

 

Thanks you!

 

Hello MR Efficiency , i dont understand the last part, "You'd have to think the chines would stand clear of the water at rest"

Can you explain again?

 

Where is the waterline when the the boat is unloaded and stationary ? If the hull is only 300kg she must be sitting high on the water.