Help Me! Planing Problems

[tecdiverdude]

i just purchased a 6m custom plate cuddy cabin. great boat. BUT just as u get onto the plane with 4 people and dive gear on board (doesnt do it with 2ppl) the hull rises normally, starts to settle onto plane, then teeters a little, then violently lists to on side or the other (effectively "falling over') nearly capsizing. it is very dangerous AND scary! i am an owner of boats of over 15 yrs and have never seen anything like this, it has bennett auto trim tabs (it also does it on manual mode) ande stabilising pontoons on the hull. PLEASE HELP ME!

 

[Silvertip]

Re: Help Me! Planing Problems

It would appear to be a trim tab malfunction. Has anyone actually observed the trim tabs from another boat when the severe listing occurs? It could be one trim tab is operating imroperly.

 

[smokeonthewater]

Re: Help Me! Planing Problems

sounds like one is collapsing

 

[Philster]

Re: Help Me! Planing Problems

Obviously, trim tabs as stated, or you got a bunch of water trapped in the hull and the weight of four people is just enough to get it over on one side of the boat.

To be clear, it falls over to EITHER side? Not the same side all the time?

 

[tecdiverdude]

Re: Help Me! Planing Problems

the trim tabs appear to be working, however the 'collapsing' idea i will investigate. it nearly always lists to starbord. by chance, would adding ballast to the bottom of the hull or filling the pontoons with water help suppress air lift under the hull? to me it feels like the boat is just balancing when im manually adjusting trim tabs, but i eventually loose her. all comments are appreciated-this is a very sever 'tipping over ' that occurs quite sudden. at around 34-38 kph.

 

[tecdiverdude]

Re: Help Me! Planing Problems

It would appear to be a trim tab malfunction. Has anyone actually observed the trim tabs from another boat when the severe listing occurs? It could be one trim tab is operating imroperly.

as in operating by itself? out of the water they function fine, which was also tried with a mate lifting up on them quite hard to try to make them 'fail' or give in, but no malfunction noticed. i believe the boat only started doing this after a long run offshore with the wife and when we returned to pick upfriends it started doing it. it could be the fuel tank (220l) may act as ballast?

 

[QC]

Re: Help Me! Planing Problems

Let's recap and confirm a few things:

1) Only happens with four people, not two, right? Can you confirm, reconfirm, Pete and repeat?

2) Happens with tabs in auto or manual mode. Are you manipulating the tabs? Can you correct for the list with the tabs?

3) Will she plane with the tabs in the full up position? If so does this problem occur with the tabs all of the way up? If it does, then it is not a collapsing or out of control tab . . .

 

[joey maneri]

Re: Help Me! Planing Problems

Sounds like the reason the boat got sold. I dont think a boat should feel like its gonna flip no matter what position the trim tabs are in. There must be another problem.

 

[joey maneri]

Re: Help Me! Planing Problems

Stabilsing pontoons? Why would they be there? Why would this boat even need trim tabs. Sounds like someone tried to improve a bad design. It looks a little top heavy in the pics.

 

[tecdiverdude]

Re: Help Me! Planing Problems

update.!
on advise from a few boat builders, i came to the conlusion that the reason the trim tabs are innefective and the boat is what is termed "chine walking" which means it is sitting too high out of the water on the very deep v hull. so i had to lower the boats position overall in the water. so i removed the engine planing fins. it dramatically made a difference. then i raised the engine up one hole to its top position. the boat now sits much deeper on the plane and doesnt try to kill us any more- it now slowly sways from spontoon to sponton - or lists with the wind, (but this is so gentle and slight now) so now i have tamed the beast- i will attempt risking the lives of more than 2 again. (as it did it with 2 in the boat when fuel was at absolute minimum) (keel balast was low) now the trim tabs are able to compensate for a 120kg man moving from one side to the other. and i hope once i add another 2 people and 4 sets of scuba gear and 4 extra tanks, it will sit on the hull and the two spontoons at one time and not sway. fingers crossed for tomorrow. any other ideas on making boat ride a little lower in the water?

 

[trendsetter240]

Re: Help Me! Planing Problems

update.!
on advise from a few boat builders, i came to the conlusion that the reason the trim tabs are innefective and the boat is what is termed "chine walking" which means it is sitting too high out of the water on the very deep v hull. so i had to lower the boats position overall in the water. so i removed the engine planing fins. it dramatically made a difference. then i raised the engine up one hole to its top position. the boat now sits much deeper on the plane and doesnt try to kill us any more- it now slowly sways from spontoon to sponton - or lists with the wind, (but this is so gentle and slight now) so now i have tamed the beast- i will attempt risking the lives of more than 2 again. (as it did it with 2 in the boat when fuel was at absolute minimum) (keel balast was low) now the trim tabs are able to compensate for a 120kg man moving from one side to the other. and i hope once i add another 2 people and 4 sets of scuba gear and 4 extra tanks, it will sit on the hull and the two spontoons at one time and not sway. fingers crossed for tomorrow. any other ideas on making boat ride a little lower in the water?

I don't think I quite follow the logic here... If you say it's chinewalking because it is too high out of the water then it should be doing this when you have less weight not more...

When you say you removed the "engine planing fins" what is this? Did the motor have a "whale tale" or "doel fin" mounted on it when this was happening? Perhaps what was happening is the fins were being submerged by the extra weight and this caused the chinewalking like behaviour.

Also what type of hull is this? It looks quite unusual and I've never seen one quite like it.

 

[tecdiverdude]

Re: Help Me! Planing Problems

yes it did have a whale tail. apparently the logic is that being such a deep v hull, it sits high out of the water- therefore not riding on a very wide section of boat- when there are 4 people in the boat there is much more weight up high and out wide of where the boat is actually in the water! so i needed to get it down so the spontoons are always in the water. i now believe with some exta fuel and other people it will be fine. this hull is designed for the very rough waters around NSW australia! it performs perfectly there but in the bays the probs occur.

 

[trendsetter240]

Re: Help Me! Planing Problems

yes it did have a whale tail. apparently the logic is that being such a deep v hull, it sits high out of the water- therefore not riding on a very wide section of boat- when there are 4 people in the boat there is much more weight up high and out wide of where the boat is actually in the water! so i needed to get it down so the spontoons are always in the water. i now believe with some exta fuel and other people it will be fine. this hull is designed for the very rough waters around NSW australia! it performs perfectly there but in the bays the probs occur.

Very interesting..please post back with your results after your next trip out.

Normally you would not see a boat, even with a deep V chinewalk at speeds that low. (were talking about 25mph here). It must be the unique hull design with the spontoons that require it sits low in the water for stability. Removing the whale tale was likely the best thing you could've done because it will lower the stern.

 

[JoLin]

Re: Help Me! Planing Problems

Glad you seem to be straightening out the handling problems. That's a very interesting looking boat- I like it.

Do you know the make/model, or the HIN?

BTW, the "leaning with the wind" condition is typical of a deep-v hull. Your trim tabs are there to correct that.

 

[a70eliminator]

Re: Help Me! Planing Problems

I had those same exact symptoms with my boat, once on plane all it would take was a small weight shift and the boat cut sideways so bad it would throw you out of the seat, you couldn't even steer out of it, all I could do is shut down, I took the big dol-fin off the cavitation plate and it never happened again.

 

[QC]

Re: Help Me! Planing Problems

Shame on all of us for not immediately asking about a flippin' hydrofoil, the initial description should've led us all to water . . .

 

[rbh]

Re: Help Me! Planing Problems

Sounds like the boat was trying to launch not plane,
houston we have a problem.

 

[tecdiverdude]

Re: Help Me! Planing Problems

Glad you seem to be straightening out the handling problems. That's a very interesting looking boat- I like it.

Do you know the make/model, or the HIN?

BTW, the "leaning with the wind" condition is typical of a deep-v hull. Your trim tabs are there to correct that.

its a custom make- there are lots of small boat companies here that make this type- they are made out of 5mm alloy plate.

 

[tecdiverdude]

Re: Help Me! Planing Problems

I had those same exact symptoms with my boat, once on plane all it would take was a small weight shift and the boat cut sideways so bad it would throw you out of the seat, you couldn't even steer out of it, all I could do is shut down, I took the big dol-fin off the cavitation plate and it never happened again.

good to see someone else has had this exact problem! im not more confident in the solution. thank you all !

 

[tecdiverdude]

Re: Help Me! Planing Problems

Sounds like the boat was trying to launch not plane,
houston we have a problem.

exactly! i swear i bought a boat not a plane. thank you , and ill keep you posted on the test today!