Repowering a Solent 6.9

Wight · 19 October 2020, 09:16

Hello all..

New to forum, just posted in the "hello" section.

I am looking to get some advice from the extensive experience in the community.

My current boat has a 150hp Yam VMAX 2stroke. While the engine is in great condition and has been well serviced, I am keen to repower this winter. My main drivers for this are (in no order):
- Better fuel efficiency (I will use year round, and would like to do some longer trips)
- The confidence of manufacturers warranty
- More power, lower rpm at higher cruising speeds
- Git rid of the noise and smell of 2 stroke!

The manufacturers plate states the boat can take up to 168 Kw but mentions nothing of weight. Does anyone know what weight these boats are rated for? I have tried searching the web with no success.

And then it comes down to what Engine and what horsepower. Taking weight out of the equation for now, I would like to aim for 200hp on the back if possible.

Does anyone have any thoughts or suggestions on what would be a good set up for this boat?

Thanks in advance
Nick.

neil.mccrirrick · 19 October 2020, 10:42

If it helps I have the same boat and have a 225hp optimax on the back

Searider · 19 October 2020, 10:47

I think you'd be fine with a 200hp.
Aim to keep the weight as low as possible.

You could ask Lee fairweather at Fairweather Marine in Fareham - he built it.

Wight · 19 October 2020, 11:05

Quote:

Originally Posted by neil.mccrirrick

If it helps I have the same boat and have a 225hp optimax on the back

Thanks Neil....I bet that flys!!

So from what I can tell that is about 225kg. Which is similar weight to the new 4cyl 200hp four strokes from Suzuki and Yamaha I think. Thats good news!

Also, how big is the fuel tank on these boats?

Thanks

Wight · 19 October 2020, 11:07

Quote:

Originally Posted by Searider

I think you'd be fine with a 200hp.
Aim to keep the weight as low as possible.

You could ask Lee fairweather at Fairweather Marine in Fareham - he built it.

Thanks Searider.. I did drop an e-mail to Fairweather marine to ask some questions, but never heard back. I'll see if there is a number and give them a call.

HDAV · 19 October 2020, 12:33

Phone number on website https://www.fairweathermarine.co.uk/

Perhaps ask them For a repower quote

Wight · 19 October 2020, 12:37

Thanks HDAV.. spoke to them earlier. waiting for a call back once Lee is back in office.

Maximus · 19 October 2020, 18:34

Quote:

Originally Posted by neil.mccrirrick

If it helps I have the same boat and have a 225hp optimax on the back

Works pretty well it does too

neil.mccrirrick · 19 October 2020, 18:36

Lol cheers matt 160 litre tank

butty · 20 October 2020, 08:03

Wight
I would have a chat to Adam at AP marine in Cowes for some advise and help repowering, very helpful and knowledgeable guy who is always available... based in Cowes which should help you...

Wight · 20 October 2020, 08:49

Quote:

Originally Posted by butty

Wight
I would have a chat to Adam at AP marine in Cowes for some advise and help repowering, very helpful and knowledgeable guy who is always available... based in Cowes which should help you...

Thanks Butty... I will him call today.

Wight · 20 October 2020, 21:13

It turns out that (like neil.mccrirrick) I have a 23inch transom on the RIB. Measured it tonight. So sounds like I am bang in the middle of L and XL. Have spoken to numerous marine engineers now, and have heard conflicting advice:

- Get an L and sit it as low in the saddle as possible (but that may still present issues)
- Get an XL and raise it up "a bit"
- Build up the transom
- Cut out some more of transom
- Get a jacking plate

So.... my head is spinning now, and would welcome any thoughts from those that have been a similar situation.

Cheers

neil.mccrirrick · 20 October 2020, 21:48

I went L low as possible and all good. No cavitation if trimmed correctly or rooster tail. Cav plate rides skimming the water on the plane. I’m happy and would not go XL. But it was a worrying choice

Wight · 20 October 2020, 22:14

Quote:

Originally Posted by neil.mccrirrick

I went L low as possible and all good. No cavitation if trimmed correctly or rooster tail. Cav plate rides skimming the water on the plane. I’m happy and would not go XL. But it was a worrying choice

Thanks Neil... that’s what I was leaning towards, but lots of mixed messages! Given the size of the investment to repower it certainly makes me nervous!!

neil.mccrirrick · 21 October 2020, 07:49

The angle of the transom reduces th length of the vertical I.e. The shaft leg. Plus modern outboards can ride higher than directly in the keel line where tradition says the cav plate is in line. All this helped me to a decision hope it helps you

Wight · 21 October 2020, 08:48

Quote:

Originally Posted by neil.mccrirrick

The angle of the transom reduces th length of the vertical I.e. The shaft leg. Plus modern outboards can ride higher than directly in the keel line where tradition says the cav plate is in line. All this helped me to a decision hope it helps you

Thanks Neil...

I’m currently leaning to either Suzuki 200hp AP or the latest Merc 200hp. Both appear light enough.

Been told the Suzuki in Long shaft is easy to get hold of, but a long shaft Merc is special order.

To a degree it will come down to what deal I could get, but still open to opinion on these two options.

What speed do people think I could achieve from a set up like this? I get around 42-44knots WOT from the 150 VMAX, but have been told going to 4cyl could blunt performance even though adding 50hp?!? 🧐