Increase outboard size on a Parker 235?

[Fitzjohnsykes]

We keep a Parker 235 we moor at Totnes and often motor 8 miles before sailing, we have a 6hp ((26 Kgs) charging) outboard and our wondering if we could increase to 8 or 9 hp (38Kgs) in order to obtain greater speed than 4 knots plus less noise.
Would we be foolish by adding more weight? Would appreciate and thoughts, unfortunately we can't ask parkers as they do not exist. With many thanks. Jennie

 

[coveman]

Would it be worth asking on the Parker owners forum? PSSA > Home

 

[Fitzjohnsykes]

Hi Coveman - thanks, we've tried that and waiting for any replies.

 

[Slowboat35]

Ask the question on the Parker-Seal website.
Genuine knowledge is available there.

 

[davidpbo]

I have a 24ft Jeaneau Tonic with 9.9 hp Yamaha 4 Stroke. It replaced a time expired Mercury 8hp 2 stroke. The displacement is 1900kgs.

4 knots does not sound that much, mine does 6 fairly comfortably I think, and I think it would take a prop with more push as power does not seem to be an issue.

Is the fuel consumption excessive?
Can you push against a current? I guess not to the degree that you might want.
Does the motor sound as though it is labouring/overloaded? If it does not it might be worth looking at the prop size and pitch and make sure it suited to the boat.

 

[coveman]

Hi Coveman - thanks, we've tried that and waiting for any replies.

Hopefully someone will reply there, but I have a 22ft boat with a Yamaha 8hp 2 stroke (27kgs) fitted with a saildrive prop, which seems very efficient. Is your existing engine a 4 or two stroke? - unfortunately once you enter the four stroke world the weight is greater and also the dimensions for fitting in a well. Obviously if yours is transom hung you don't have that problem.

 

[LONG_KEELER]

I would have thought that 6hp would be fine to get somewhere near hull speed.

As mentioned, moving up from 6hp means half as much weight again if a four stroke, and it might not fit your well.

If you don't have a sail drive prop ( mickey mouse ears sized blades and pitch change) it might be worth trying.

A rev counter would help to solve the problem. Don't suppose you know anyone with a Tiny Tac rev counter you could borrow ?

 

[Munz]

Also would have expected (near) hull speed from a 6hp.
Sounds more like a problem with your current setup rather than needing more HP.
Would start by checking you have the correct "high-thrust"/saildrive prop, if you don't there is a company "Solas" that sell aftermarket high-thrust props for most of the common outboard manufactures.

 

[northwind]

We keep a Parker 235 we moor at Totnes and often motor 8 miles before sailing, we have a 6hp ((26 Kgs) charging) outboard and our wondering if we could increase to 8 or 9 hp (38Kgs) in order to obtain greater speed than 4 knots plus less noise.
Would we be foolish by adding more weight? Would appreciate and thoughts, unfortunately we can't ask parkers as they do not exist. With many thanks. Jennie

Change the prop before the engine. I doubt more power to be the answer, I had a 9.8 on a super seal.
What prop do you have on it? Is it a low thrust prop or one intended for a planing boat?

 

[Fitzjohnsykes]

Change the prop before the engine. I doubt more power to be the answer, I had a 9.8 on a super seal.
What prop do you have on it? Is it a low thrust prop or one intended for a planing boat?

Many thanks. I have know idea what type of prop is on the outboard but will now take a closer look!