New Boat Porpoising

Correct me if I'm wrong, but I think the Traveller boats are a stripped down economy version of the Signature boats, the hull shape would be the same anyway.
http://www.youtube.com/watch?v=URI1Q29LBIU
This is the open boat version, not a big boat by any means and a bit narrow gutted looking at the video.

 

Besides all of the stuff you're doing with trim and weight distribution, the other thing that will cause porpoising is hull deformation, such as hook. I know it's really unlikely, but could the hull have somehow been warped during manufacturing, such as popping it from the mold too early? Try running a straight edge or string line down the keel just to make sure it's true.

The aft batteries sound suspicious too. Can they be located more amidships, such as under the console?

 

He says the dealer has checked the bottom of the boat with a straight edge. The hull has an unusual variable deadrise shape, so I dont know how definitive that would be in determining whether it conforms to the design shape. The builders are a big concern with decades of experience, so it seems unlikely they would be turning out boats that develop rocker.

 

Take it back, it's unacceptable.

-Tom

 

Sorry, but in boat " Highly Respected Brand " is very elusive, and just a marketing tool, far from reality.
So many " Highly Respected Brand " delaminate, lost the keel, take on water, lousy plumbing and electrical systems and so on.
Lister

 

I agree with Tom, it's a new boat, it's unacceptable.

Installing Trim Tabs will stop the porpoising for sure, but will not fix the underlying problem. If you really like the boat and want to keep her make them install a set of trim tabs.

Steve

 

The guy who designed and built these boats died a couple of years ago, but was near enough to a genius in power boat design over decades. ( John Haines snr.) So I think the hull wouldn't have had some vice designed in to it. As I said earlier it is difficult to see where the problem arises.

 

Purposing

hi,
We had prop spin in the water on a 1/4 trim @6000 RPM with 19 deg prop, went back to 17 deg prop no more prop spin.

The Boat dealer & Company Rep have been great, l just don't understand it, trying to get my head around it.

Regards Andrew.

 

Hi,
The wedge has now been removed, The more power that l apply it seams to solve it to agree, it still lists a bit to the to the RHS.

Regards Andrew.

 

You said yours is the only boat with a merc on it, lets look at this.

What engines do the boats that work ok have , what is the difference --weight especially. I know you are thank full for your dealers help but from where im sitting its not that impressive.

Measure the position of the engine on the transom from off centre, or is it dead centre?

Is the steering position left or right,--- no that wont make a difference but the weight of the person sitting in it will.

Are you by any chance an extremely large gentleman?

We have a weight x torque conflict.

 

The engine hasn't been properly broken in yet or retuned from the factory setting, yes?
Put the required hours on it at the throttle setting specified and the get the engine tuned up by someone who knows what they're about. This will significantly change the engine response and trimmed nose up porpoising can be affected by this. If this doesn't satisfy you, then take it back. If you were trying a wedge kit, you were trying to get the nose down more at full down trim? nose down porpoising is a different matter related to hull design.

 

No l am not a small bloke, l am 121 kg, But when l stand just past the COG at the wheel, the boat sits flat and drives ok, The boat dose not purpose at full trim.
95% of the boats run the Suzuki 70 hp@158 kgs and their are only a hand full that run the Yamaha's 75 hp@168 kg, Max Motor weight is 170kg

Regards Andrew.

 

They are water testing her today again, So l will have to wait for it to come back, l will under take all the above and get back to you. ASAP.

Regards Andrew

 

121KG !!! sorry but does it porpoise with out you in it. What if some one else drives it?

 

Hi,
No diffidence Same thing, But it dose rock and roll a lot, In a small swell that is about 2.5 mtr to 3.0 mtrs between centers with a depth of about .250 to .300 mm high, it duck and weaves and and then it starts to purpose again, But at full throttle it dose improve a little, not much, l just don't get it.

Regards Andrew.