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Old 17 May 2010, 11:59   #11
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Once you're planing -2" typically = +400rpm

Since you only made 3500rpm (and WOT should be around 5500rpm) and couldn't plane I'd drop more than 2" of pitch. 17" is probably optimistic; I'd try a 15"
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Old 17 May 2010, 14:59   #12
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Ocean 6.5 is rated to carry 1000kg
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Old 17 May 2010, 15:02   #13
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Dan, I guess your rib has a max loading of circa a ton.
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Ocean 6.5 is rated to carry 1000kg
is there a prize?
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Old 17 May 2010, 15:13   #14
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is there a prize?
Well done Willk!

...and thanks Tim (out of interest, where did you find that...have I missed something on the Ocean site?)

Captn Jack...take your point, will see if I can source a 15 to try...

Gordy, you are right, 6 divers is okay if not ideal, but space is going to be an issue with all that kit....given the weight issue, a second boat carrying gear is looking to be the best option.

Simonb...thanks for the recommendation /contact....will pick their brain too.

Thanks all....RIB net comes up with the goods again! Despite probably using a second boat, the smaller prop will be better for the boat when carrying 6 divers generally....will let you know what we end up with.

Dan.
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Old 17 May 2010, 15:43   #15
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6 divers, loadsa kit, extra air, and only a 6.5m boat - I really do think you are looking at a second boat even if only for safety.I don't know where you are going but if its somewhere where it might rough up while you are out you will be seriously struggling with a boat loaded like that (and I assume your tests have been made on flattish water). Its gonna be a whole lot harder to get it on the plane going uphill! and I really wouldn't like to be kitting up that crowded.
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Old 17 May 2010, 16:14   #16
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A second boat would be good, however, in good conditions (not many divers actually dive in bad conditions) it sounds do-able however, as your max manufacturers payload is 1000kg your insurance would be void if this is broken. We've run 8 divers and 2 crew on a 5.5 delta - cramped but all on single tanks and no ponys, not that teckie, sorry.

As wavelength said kitting up cramped is not good either, for diver, boat or crew. When our little boat did run loaded up it did not take much to knock her off the plane then you end up at full throttle climbing swell or waves that arent really that large with almost nothing in reserve except your own nerve.
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Old 18 May 2010, 06:28   #17
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Spoke to the VERY helpful lady at Steel Developments ....after discussing the various weight scenarios and revs achieved etc, she has recommended a 15 pitch four blade.....one winging its way here now....thanks for the recommendation!

Will need a second boat for the additional gear /that project, but following my conversation with them the 15 sounds a good solution for when we are operating up to our 1 tonne max capacity (obviously excercising discipline not to over rev if not laden....)

Will let you know how it performs whe we get chance.

Thanks all

Dan
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Old 18 May 2010, 13:22   #18
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she has recommended a 15 pitch four blade.....one winging its way here now....thanks for the recommendation!
Yeah I thought a 4 blader might help. Its certainly a heavy boat if the payload is only a tonne, you'll lose some more off top end speed switching to four though, IMHO and you will get more slippage from hole shot, but I found cornering grip improved at full bung, and the stern didnt drift as much, but that was on a fairly light boat,.. will be good to hear how you get on
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Old 24 May 2010, 16:03   #19
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will be good to hear how you get on

To close this one out....have been trialling the new 15 pitch 4 blade prop with 8 up and weight.....hole shot great, top end reduced to 32 knots (more than enough laden...really happy at 25 knots)....biggest surprise is that even when we ran with just three on board, it still didn't rev past 5300rpm....max engine revs 5700rpm according to literature....cant get my head round this...not complaining, just thought it may /would have overrevved?

Really very pleased....thanks for all the assistance....big thumbs up to steel developments....recommended

Dan
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Old 24 May 2010, 16:46   #20
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The revs could be to do with switching from 3 to 4 blades, you've got more surface area.
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