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Old 05 March 2008, 09:01   #11
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Country: Canada
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Make: Gemini
Length: 4m +
Engine: 40hp 2 str
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Couple more things to consider;

First off what is the max power this boat is rated for? If it is a 4.2m boat, it is probably 40hp, if 4.7m, probably closer to 60hp.

A 25hp 2-stroke will weigh somewhere around 45-52kg. A 40hp or 50hp 2-stroke will weigh somewhere from 70-80kg. If the weight of the fabric/transom unit is in the ballpark of what I suspect it to be, your going to need a way of hauling/hoisting/maneuvering/storing a fabric & transom unit that weighs as much as a 40/50hp 2 stroke.
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Old 05 March 2008, 10:22   #12
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You're right about the weight.
JBT told me 80kg.
There is no way that sib is 80kg. When I collected her yesterday it was in two packages on a pallet, one being the fabric and one I think the floorboards.
Two men could just about lift each one and set it into the small boat I also bought.
The fabric is hypalon and I would estimate at least 120kg...ish all up.

As an aside issue, I purchased separately a 15hp Yam short shaft for the small boat but the transom is about 3" too deep so I'll just use the Yam on the Gemini in the meantime. It should be powerful enough to push me around against the tides as it's main use will be to service moorings at slack water.

Boat is 4.5m
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Old 05 March 2008, 10:33   #13
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That boat should hold up to alot of very heavy useage. It certainly isn't your garden variety SIB designed to fit in a car trunk (boot). I'd bet that the transom thickness is near double what you'd see on most SIBs.
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Old 05 March 2008, 11:03   #14
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Engine: 10hp Yam / 150hp opt
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The Navy have these Geminis on the back of their P2000 patrol craft. These have a 20hp Mariner 2 stroke with prop guards. Fairly sluggish with 3 or more persons on board - but probably due to the prop guards as much as anything.

When I was a student and in the RNR we had the same / similar Geminis with 35hp 2 stroke Evinrudes. They flew with those! Bit of a handful mind.
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Old 06 March 2008, 14:56   #15
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I took the bathroom scales and weighed the various bits which make up the sib. The three packages in the first pic from top to bottom are the keel section, the floor and the fabric of the boat.
30kg, 60kg and 60kg respectively.
As there are no instructions with the sib I hadn't a clue what the items were in pic 2 but Jason at JBT told me they are the sections that make up the keel... thanks for that.
The next pic shows the fold up floor which is incredibly heavy. The green bit of wood with the groove cut out I think is part of the rear section of floor where it meets the transom.
Pic 4 shows the sib unfolded and finally the transom.
I ran out of time to complete the job today but will try tomorrow.
I'm starting to think my idea of inflating /deflating after use is going to be wishful thinking... I feel a trailer purchase coming on.
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Old 06 March 2008, 18:50   #16
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YIKES !
150 kilos without a motor...its really heavy!
The transom looks twice as thick as the one on my Searider.
It should last forever though! Good luck!
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Old 09 March 2008, 16:19   #17
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I used to use one of these when I was an instructor at the Sea Cadet Corps, we ran with a Mariner 40hp short shaft with prop guard.

Was great fun on flat water, but had a nasty habbit of bending and flexing in heavy conditions, make sure you keep your fingers away from the floor boards when under way or might lose them.

As for the bottom boards the flat one that is taped in the middle goes into the boat first at the stern. It should have blocks to guide the keel assembley into the transom. Then the heavy bottom boards and finally the wood pannel for the bow which is a complete pain to fit and takes a lot of kicking whilst pulling the front of the inflatable up.

As for deflating and reinflating I would suggest you get a trailer as the boat will last a lot longer being left inflated than rolled up.
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Old 18 November 2008, 11:57   #18
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Mercury 25hp on this SIB

I also bought one of these Geminis from JBT earlier this year.
I was considering a 2006 25hp Mercury 4 stroke to use with the SIB on standby/safety boat duty. The outboard is available from a dealer and seems to be reasonably priced.
Any comments good or bad on this unit.

Thanks
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Old 18 November 2008, 19:40   #19
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Very good things to say about the Merc 25. We put them on our Commandos and they punt them along very nicely. Good fuel consumption, sensible shallow drive system (only one setting, but not a disadvantage where we were). Only problem we found was that the throttle would stick for a few seconds if run at flat chat - traced to a dodgy throttle rod. That was only on one unit though. I'm not normally a four stroke person but I liked it!

You can indeed carry them fairly easily - got to be a plus!
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Old 21 November 2008, 17:34   #20
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30hp 2-stroke would be your limit. I use to manhandle a 25hp Yamaha short-shaft by myself and it was challenging, especially on a steep or green slipway. Any more HP and you risk damaging your back and the engine itself!
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