Control problems

[Damightybigfoot]

First sorry if this is the wrong forum to ask in but it's the most suitable I could find...

I have recently purchased a picton 159gts which has a johnson v4 140 on it, the problem I have is when I accelerate the boat has a lot of bow lift to the point it hasn't got much acceleration, once the boat planes it accelerates hard but it takes ages to plane (even worse with a skier to the point the skier cant get up as it drags too much)

Also the engine revs out to 5500 with the prop gripping but will go to 6000rpm with cavitation, the engine itself runs mint but something which we cant figure out is causing it too dig in (acting like I'm trying to accelerate with the engine trimmed out but engines trimmed in, even got trim bolt removed) anyone have any experience with this hull or this problem that could offer advice on how to diagnose this issue

 

[Texasmark]

Sounds like you might have a stern lifting prop rather than bow lifting. In Mercury terminology, one such bow lifting prop is the 3 blade Laser II. Google the prop and read up on the attributes of that kind of prop. Then find your prop and read up on it's attributes.

140 on a 16' boat is punching out pretty hard, plus weight could be a problem especially if your fuel and batteries are in front of the transom. Last you could have a hook in the hull usually caused by sitting on a trailer improperly supported, or filling with rain water and sitting for extended periods, or damage due to stringer rotting.

A hook is easy to see, just get down at hull level and look stem to stern, or stern to stem.....put a straight edge on it if necessary. The hook will be concave.....won't touch the straight edge in the middle area of the hull...generally speaking, usually toward the transom related area.

Ski rope tied to (vertical) middle of transom...lifting eyes....one on each side with a yoke and roller? If on a tower post, that would aggravate the problem

 

[Damightybigfoot]

Sounds like you might have a stern lifting prop rather than bow lifting. In Mercury terminology, one such bow lifting prop is the 3 blade Laser II. Google the prop and read up on the attributes of that kind of prop. Then find your prop and read up on it's attributes.

140 on a 16' boat is punching out pretty hard, plus weight could be a problem especially if your fuel and batteries are in front of the transom. Last you could have a hook in the hull usually caused by sitting on a trailer improperly supported, or filling with rain water and sitting for extended periods, or damage due to stringer rotting.

A hook is easy to see, just get down at hull level and look stem to stern, or stern to stem.....put a straight edge on it if necessary. The hook will be concave.....won't touch the straight edge in the middle area of the hull...generally speaking, usually toward the transom related area.

Ski rope tied to (vertical) middle of transom...lifting eyes....one on each side with a yoke and roller? If on a tower post, that would aggravate the problem

The prop came with the boat, it has no imprinting on it nothing too say what it actually is... the leg is the old Johnson fitting with a captive nut and split pin rather than a spider so 4 blade props are virtually impossible to find.

In term of weight the engine weighs less then my brothers 90mariner on his 17foot boat as it is a premix engine no vro

Hull is solid all way through, on a roller coaster trailer, no signs of damage anywhere.

We ski from a pole as it has no hooks however it still has a considerable amount of bowlift without a skier

 

[southkogs]

Dunno' that boat from here in the States, but are you sure you're not overpowered? The little bit of lookin' I could find on 'em started me wondering that.

Cool lookin' boat. Welcome aboard.

 

[Carl1783]

Sure seems to me like a 140 on that boat is overpowered. A quick google search shows most boats of that model with 75-90 hp outboards.

Does the boat have trim tabs? That might help band aid your issue, along with a different prop.