picton 150 gts bad handling

[studiono1]

i have recently bought a picton 150 gts with a suzuki 65dt outboard she goes great ( in a straight line) however when you turn left she starts to turn as normal banking slightly then she sudenly and violentlt flips over to the left you get the impression that if you hold your course and do not let go of the steering wheeel she will flip over at the same time the prop seems to come out of the water and the enging over revs it realy ifeels quite dangerous
i have owned several boats over the past 20 years all of which have been inboard either direct drive deltas and jet boats and never had anything like this before

please help

 

[Nautorius]

OK,

The good news is that your boat is not over-engined (Which most were). I think you will find you are turning in with the engine trimmed out too much. When going in a straight line you can trim the engine out (up) to help top speed but it will wreck stability if you turn in quickly. Try trimming her full in before turning. Outboards are far less forgiving than inboards!

Hope that helps

Paul

 

[studiono1]

thanks for advise i have tried it with the outboard fully down and it makes a little difference

cheers

Paul

 

[colingr]

Sounds like the chines are digging in. I've driven an Osprey RIB that did something similar but only during very tight turns or crash stops.

Nothing could be done with it apart from being gentle in the turns for that particular boat.

Does it behave the same turing port and starboard or just one way? If only one way could the outboard be misaligned?

 

[studiono1]

no just turning left not turning right its fine

 

[colingr]

Either some serious prop walk or outboard out of alignment. The engine mounts are nice and secure I assume and it's not moving on the transom at all?

Actually re-reading your first post you are saying that in effect it is exaggerating the turn rather than flipping outwards. More like a skid effect?

Sounds like it's behaving like a bike when it lets go?

Prop effect might be a cause but I've never experienced it as dramatically as that.

 

[Nautorius]

no just turning left not turning right its fine

Sounds to me like the outboard may have been fitted 'off centre' to the left of the stern. You need to measure that to rule it out

Paul

 

[Chris_d]

Outboards can be fitted off centre to counteract the prop torque normaly to the left for a RH prop, if it has you could move it back but then the boat may list too much to the left. You may have to experiment a bit to find a compromise between straight line stability and turning, the outboard should also have trim fin on the cavitation plate which may need adjustment, they can move out of position after a while and need repositioning.

 

[studiono1]

thank you very much for your advise i will measure the outboard position and let you know how i get on top marks for this forum i wish i had found it earlier in my boating life i guess i could have saved myself a fortune in marine dealer fees
thanks again
Paul

 

[colingr]

Best of luck with this. Please do come back and tell us what happens.

 

[studiono1]

the one thing i forgot to mention when going in a straight line if i was to let go of the wheel the boat would turn left on its own if i left it the out bourd would slam into left hand lock

 

[colingr]

Before moving the outboard about have a good look at the skeg. Sounds like it might be on the skew. It should be pointing pretty much in line with the prop shaft(if you see what I mean) and not off to one side.

Where are you based?

 

[Nautorius]

the one thing i forgot to mention when going in a straight line if i was to let go of the wheel the boat would turn left on its own if i left it the out bourd would slam into left hand lock

OK,

That is a bit different. The only time I ever had this happen was on an 85dti Suzuki fitted with a Dole Fin (The after market black fin that is bolted to the cavitation plate!) Once the left hand bolts came loose moving the left fin out of alignment with the right and causing the boat to pull badly to the left!

One last thing to check is on which side are the Petrol Tank and Battery. Even little things like that on a 15ft boat have an effect.

Good luck

paul

 

[sarabande]

Some quick questions.

1 Do you have the right prop for the boat and engine ? Any numbers ?

2 What about the fore and aft balance of the boat ? Is she trimmed down by the head when stationary ?

3 How far below the bottom of the transom is the o/b cavitation plate and prop ?

Any pics ?

 

[Davy_S]

the one thing i forgot to mention when going in a straight line if i was to let go of the wheel the boat would turn left on its own if i left it the out bourd would slam into left hand lock

Erm, would have been better if you mentioned this before!
Your trim tab, underneath the cavitation plate needs ajusting NOW, you should be able to let go the steering and the boat tracks staight.
Looking at the boat from the stern towards the bow, if it turns to the left, port, the trim tab needs to be moved out to the left, to counteract this.
Do this untill the boat tracks straight, then come back and report. Better to get the simple things right first.

 

[studiono1]

ahh that might be it when i bought the boat the previous owner had knocked the skeg off and has had a aluminium replacement welded on and is is deffinatly not straight i will posta picture later

 

[oldgit]

the one thing i forgot to mention when going in a straight line if i was to let go of the wheel the boat would turn left on its own if i left it the out bourd would slam into left hand lock

I started out with one of these years ago,the package supplied normally with a 40hp non t&t on the back.
Mine was fitted with a 55HP Suzuki in the end.
It did have a habit of digging in rather violently sometimes but boat never felt as though it was about to turn over.

 

[Bilgediver]

Some quick questions.

1 Do you have the right prop for the boat and engine ? Any numbers ?

2 What about the fore and aft balance of the boat ? Is she trimmed down by the head when stationary ?

3 How far below the bottom of the transom is the o/b cavitation plate and prop ?

Any pics ?

Likewise my thoughts are is the prop too near the surface also over pitched/and or over size. I suspect that reducing prop size might reduce this effect however at the expense of speed if the boat is already at max revs.

 

[rob1699]

I had one of these with a 55 twin cylinder yammy about 20 years ago - did exactly the same. Prop out of the water in a hard turn - it would put the absolute fear of god in SWMBO!

I tried different pitch props, raising/lowering the outboard height, attaching a doel fin, altering the trim (mine was non PTT) all to no avail. It was even worse when pulling a skier.

I could be wrong, but I fear its just a characteristic of this hull.

Got so fed up with it I changed it for a Fletcher 155GTO which handled like a dream.

Rob

 

[Kawasaki]

the one thing i forgot to mention when going in a straight line if i was to let go of the wheel the boat would turn left on its own if i left it the out bourd would slam into left hand lock

Ok, thats cos the way the prop turns
As others have mentioned there are a few things to consider and rectify.
1. the 'cavitation plate' has to be aligned with the keel aft.
Level with the deepest part at the transom, plus in the same 'plane' if poss
2. You need a trim/anode gadgett to off set the 'prop wash'
3. Not always does the outboard need to be 'central' on the transom
4. Some small 'speed boats' need very little 'trim' and when trimmed out too far problems arise such as you are experiencing
5, 'Dole Fins' as mentioned can actually be more trouble than help, especially with symptoms you are describing
6. Yep, prop size and pitch is important

You need to check/remedy all of the aforementioned.

Your Picton will work if correctly set up.
Helmed/driven em with 40 upto 90 hp
Yours is Ok as Nautorious said.