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Old 25 July 2012, 12:17   #1
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Best small rib for fifty knots plus

Hi All
I currently have a humber 5m assault with a 90 yam on it,
I realise the shortcomings of this boat as it is fairly over powered and not really being used as intended.
In the corner of my garage is an identicle 90 yam two stroke.
So I need a secondhand rib around 5 to 6 metres in length with a nice deep v ,high mounted tubes and plenty of chines/spray rails on the bottom that I can bolt the yams to.
I also have a pair of manual 4 inch jack/set back plates if needed.

A possibility is to flog the yams and buy a merc XR2 or similar, but I like the idea of twin engines for 'get you home' ability.

Your thoughts please Gentlemen.......

And any tips on transom strengthening also welcome.
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Old 25 July 2012, 12:42   #2
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I have a 4.7 Searider hull console and trailer for sale although it's only rated for a 70........
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Old 25 July 2012, 15:33   #3
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I bet the SR4.7 wound't do 50kts with a 90hp on....
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Old 25 July 2012, 15:42   #4
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A Searider 6.0m will probably take a pair of 2-stroke 90s. Thing with twin set ups is more weight (twin batteries), seperate fuel supplies, more maintenance, etc. Here's one with twin 60s for reference. Avon Sea Rider 6.0m Boats for sale UK, Avon Used boat sales, Avon Inflatable Boats For Sale 6M commercial Avon searider - Apollo Duck

50 knots... no idea?
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Old 25 July 2012, 15:55   #5
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Interesting one. If you're prepared to throw caution to the wind, I think that you may get quite close to your target.

You need a hull and transom capable of dealing with the weight. The hull will need to be "fast" and lightly loaded. You'll have to balance the load/fuel out carefully. The jack plates aren't the maddest thing ever suggested.

Obviously a large single will be quicker. You are presumably aware that a near 50kt 6m RIB will only be "usable" on the flattest of water and will be as scary as fkk?

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Old 26 July 2012, 10:07   #6
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Yes I know it'll only go that fast in flat water,I had a concorde race hull a few years ago that would touch fifty before trying to chine walk into the next dimension. It was best with a bittle of a ripple on the water to keep it unstuck.
However that could have been sorted if it had been set up professionally.
The 90 yams seem to have the best power to weight ratio around and I was thinking that the jack plates would make setting up easier.
Has anybody ever cut and shut a phantom,ring or similar powerboat into a rib ?
Is it do-able ??
I know a guy who is a hot shot laminator.
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Old 26 July 2012, 12:47   #7
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Quote:
Originally Posted by spartacus View Post
A Searider 6.0m will probably take a pair of 2-stroke 90s. Thing with twin set ups is more weight (twin batteries), seperate fuel supplies, more maintenance, etc. Here's one with twin 60s for reference. Avon Sea Rider 6.0m Boats for sale UK, Avon Used boat sales, Avon Inflatable Boats For Sale 6M commercial Avon searider - Apollo Duck

50 knots... no idea?
6.4m with twin 115etecs WOT 5750rpm 40kn if I'm lucky with the wind behind me going downhill. If I stripped out all the toys, took the "A" frame down & ran low fuel I might get another 5kn, but where's the fun in that If I went up a pitch in prop & kept the weight down I might touch 50 in perfect conditions. It's always going to be a compromise between speed & allround balanced, well behaved boat, unless you just want the out & out speed.
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Old 26 July 2012, 13:05   #8
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This guy claims he can do 48 knots+ in a Hydrosport 636 with one Suzuki 140, you loose some power in a twin mount, so it might be comparable to twin 90? This is also the old hull design, the new might be faster? The designer is on the forum sometimes...
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Old 26 July 2012, 13:10   #9
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Quote:
Originally Posted by Pikey Dave View Post
6.4m with twin 115etecs WOT 5750rpm 40kn if I'm lucky with the wind behind me going downhill. If I stripped out all the toys, took the "A" frame down & ran low fuel I might get another 5kn, but where's the fun in that If I went up a pitch in prop & kept the weight down I might touch 50 in perfect conditions. It's always going to be a compromise between speed & allround balanced, well behaved boat, unless you just want the out & out speed.
Fine for the Med, but sea conditions constantly change so the practicalities of 50 knots are restricted to a few flat calm days. Give my a rough weather boat any day.
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Old 26 July 2012, 13:30   #10
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Fine for the Med, but sea conditions constantly change so the practicalities of 50 knots are restricted to a few flat calm days. Give my a rough weather boat any day.
Absolutely I'd much rather feel comfortable at 20kn in the lumps than cacking my pants at 50 on a flat calm sea (let's face it how many times has that happened this year) However the OP wanted a small 50kn RIB, I doubt that such a beast exists outside a specialist racing setup. A "bog standard" production RIB would have to be overpowered to get to that kind of speed & would probably chine walk like buggery, clean undies anyoneMy last RIB was a RC585 with a 175 FICHT on the back. That topped out at 47kn and was "interesting"
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