Have I just gone too big!??

Benbound1617 · 29 December 2018, 19:43

Hi all, new to the forum and just acquired my first rib. It’s a project, early 1990s Humber destroyer I think 5.5m
I’ve got a 150hp Yamaha v6 to go in the back. It’s 15kg over the transom weight, big question is will this be a problem the main thing is it has to be safe to would welcome any thought from more experienced rib users

Thanks

jeffstevens763@g · 29 December 2018, 19:49

What's it rated at hp wise if 150 I would go with it personally

Benbound1617 · 29 December 2018, 19:52

I think the modern version is 115hp which is where I got the transom weight from but there is no plate on this one to tell me unfortunately

Seaflyer02 · 29 December 2018, 19:57

I know the old 5.8 Destroyer was rated for 150 so the 5.5 would probably have been around the 130hp?

jeffstevens763@g · 29 December 2018, 19:58

Quote:

Originally Posted by Benbound1617

I think the modern version is 115hp which is where I got the transom weight from but there is no plate on this one to tell me unfortunately

I would contact Humber for a spec before doing anything they will advise you

Xk59D · 29 December 2018, 20:35

150hp v6 on a 5.5m, you asked about being safe...I wouldn't even contemplate putting that on there buddy.

Pikey Dave · 29 December 2018, 22:18

It’ll be reight [emoji6]

willk · 29 December 2018, 22:29

Quote:

Originally Posted by Xk59D

150hp v6 on a 5.5m, you asked about being safe...I wouldn't even contemplate putting that on there buddy.

But a 400hp Allison gasturbine would be just amazing...

http://www.rib.net/forum/f36/gas-tur...tml#post777198

jambo · 30 December 2018, 00:08

I had a 150 hp v6 on the back of my 5.85 for years an it was fine.

nugent · 30 December 2018, 08:32

Also had a 150 merc on a 5.5 Humber

Click image for larger version

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Views: 500
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ID: 128080

Went well with no issues and I know it's still going now after 8 yrs

Benbound1617 · 30 December 2018, 08:52

Thanks all for the comments. Il stick with it and post pics as the boat progresses

Stresspill · 30 December 2018, 10:58

First check if the transom is solid. For that vintage of a boat it could be mush. Don't know the construction material though. My SR6 is foam cored there and still completely solid it's from 1991.

jwalker · 30 December 2018, 13:44

Quote:

Originally Posted by Stresspill

First check if the transom is solid. For that vintage of a boat it could be mush.

I see you've selected a good name for yourself....

CJL · 30 December 2018, 23:05

I had a 5.5m Humber with a 150 Optimax. Loved it and it was an incredibly fast boat.

The previous owner had made some serious transom modifications to it which were to a very high standard and made me feel a lot more comfortable with it.

CJL

carldalmas · 31 December 2018, 01:02

Quote:

Originally Posted by nugent

Also had a 150 merc on a 5.5 Humber Attachment 128080

Went well with no issues and I know it's still going now after 8 yrs

They can be dangerous
when overpowered ! As air gets under tubes and flips them over !
Main thing remember you have no boat insurance
if the hull is rated for a lower hp engine
Check your cover
Great fun if you know what your doing keep bow down !

boristhebold · 31 December 2018, 08:30

If it's over the transom weight then yes of course you have a problem. Weight limits are worked out by boat manufacturers and are there to comply with regulations etc etc and for safety.

So your question, "will it be allright ". It depends upon how you are as a person.

worse case scenario

lets assume you have managed to get boat insurance.
you go out and you have a serious accident where someone gets seriously hurt, perhaps losses a leg and cant work again.
legal teams involved and claims etc start to fly, your insurance company says you insurance is invallid because your over the weight limit in terms of engine on back.

person who gets hurt has to sue you personally for damages and this all takes a few years to be settled through courts, person injured gets into a terrrible financial situation waiting for the courts to decide, finally they do and you get a huge bill for compensation and are now bankrupt, have lost everything and it still does not cover the care needs for the person injured.

yes a bit over the top or is it ?

for the sake of a few HP is it really worth the potential disaster ?

its really just like someone who has no insurance for their car deliberately.

jwalker · 31 December 2018, 13:13

Worry beads...

beamishken · 31 December 2018, 16:47

Wow for probably the first 20 years I owned a boat i never insured it. We lived to tell the tail.
Back in the 90s engine ratings were a bit of a shot in the dark and many builders saw it as a selling point to rate their boats to big engines. The newer model of the boat may well have a lower hp rating as the RCD gave specifics for hp rating not previously applied.
15kgs overweight is less than the weight of a small aux and no one would question carrying an aux on the transom

Jeff · 31 December 2018, 16:59

I had a 5.5m Cobra (1999) with a 150 Opti and never felt it was overpowered.... or unsafe.

Benbound1617 · 31 December 2018, 17:06

That’s a big help thanks. I’ve had boats for over 30 years and firmly believe that you can get your self into trouble in almost any craft no matter how compliant if you don’t treat the water with respect.
Sounds like it shouldn’t be too over balanced which was my big worry, I’ll be taking it steady and adjusting speed for the conditions but fully take on board the variety of commonest people have made, particularly re insurance. Thanks again massive response to a first post!!