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Old 08 October 2013, 11:26   #21
ncp
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Sometimes with jetdrives they actually put in a 1:1 transmission with a reverse (instead of just a disengage to neutral). People claim that this is good for clearing weeds/kelp from the drive when necessary.
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Old 08 October 2013, 11:51   #22
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Unless it is a Castoldi jet that has the correct built in gear ratio for the boat and an electric neutral clutch removing all need for a transmission. With Castoldi you save save a huge amount of space inside the boat as the engine can mount direct to the output shaft using only one coupling. The jet units I am using are 2.5 metres long and 1 metre wide with a output ratio of 1- 1.5 Alan P
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Old 08 October 2013, 11:55   #23
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Originally Posted by Alan Priddy View Post
Unless it is a Castoldi jet that has the correct built in gear ratio for the boat and an electric neutral clutch removing all need for a transmission. With Castoldi you save save a huge amount of space inside the boat as the engine can mount direct to the output shaft using only one coupling. The jet units I am using are 2.5 metres long and 1 metre wide with a output ratio of 1- 1.5 Alan P
So, you're saying ALL jet drives (that you know of) except Castoldi need a regular old transmission?

Good info. I didn't know that.
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Old 08 October 2013, 12:51   #24
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Quote:
Originally Posted by Alan Priddy View Post
Unless it is a Castoldi jet that has the correct built in gear ratio for the boat and an electric neutral clutch removing all need for a transmission. With Castoldi you save save a huge amount of space inside the boat as the engine can mount direct to the output shaft using only one coupling. The jet units I am using are 2.5 metres long and 1 metre wide with a output ratio of 1- 1.5 Alan P
Having looked at the Castoldi website the pics are exactly as i pictured, no drive shaft.
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Old 08 October 2013, 15:27   #25
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Nice boat!!
looking forward for videos.
Any idea about petrol consumption per mile @/ speed ?
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Old 10 October 2013, 11:12   #26
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I am expecting a price and will post it. Adam Younger did a good job on the hull. The deck and engine box is our design and for the initial tests we only had a laminated plywood deck, no engine box and a remote fuel tank. The first results were so encouraging that we quickly made a deck and engine box mould. The engine box had to consist of two sections due to total length. Also it had to be service engineer friendly. We have a 5 axel fully auto CMS m/c for making plugs and moulds so this was more or less an overnight job. The moulded deck also reduced the weight of the rib and that was the idea. Also a moulded deck and engine box will enhance any rib.
Andre - the boat really looks like a very nice and serious piece of equipment, congratulations! The layout looks a bit like the jetboats Delta made end 90ies for the MOD (have one myself and converted it to outboard) I like the way you put the silencer at the lost space around the drive shaft !
Did you lower the jet intake outside of the hull to avoid cavitation issues on short / steep waves or is there another solution for that (possible) problem?
My boat was with the jet very tricky on the helm on speeds below planing. Was this considered in the design of the hull or will the boat have some foil at the stern to cope with the effect that the boat tends to go to all directions except the one you want? (=applying constant corrections to the helm)

@ NCP :speaking from experience with a hamilton HJ212 unit it is in particular the neutral setting which is interesting in a gearbox with inboard/jet (so you can idle the engine without pumping water) which makes the boat much more easy to handle instead instead of start going everywhere after you started the engine ...
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Old 10 October 2013, 11:43   #27
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Many thanks for all the nice comments and no thanks to those who high jacked my thread yet again

I am yet to see the rib on the water as the last time I saw her it was before the moulded deck and engine box were installed.

I will add the questions to my list and try to get the answers soon
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Old 29 October 2013, 10:51   #28
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Footage from the first test on the water Wisla (Vistula) river in Poland where there is a lot of shallow water



more to follow
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Old 29 October 2013, 10:55   #29
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and another one

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Old 29 October 2013, 10:59   #30
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