40' Outlaw Upgrades - Twin 900Sc to 1000hp Duramax Diesels
11-02-2020, 08:29 PM
#951
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Highest you can go on a #6 or #8 is 1.15. No gears exist to do an overdrive ratio.. That's the one advantage to both of the gear drop box designs. I'm currently considering the gear ratio options vs prop options out there..Now's the time if we want to speed up that prop shaft. Or stick with slower shaft speed and big diameter and pitch.
11-03-2020, 06:00 AM
#952
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Zf does make boxes that can have overdrive ratio,s , but cost $$ , Ralph in Clearwater Ace systems , has units for sale that can speed up shafts , not so sure it is a real FNR transmission .. give him a call : 727-243 -2219
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2187 (11-03-2020)
11-03-2020, 01:50 PM
#953
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Use some Arneson drop boxes you can do your counter-rotation in the dropbox as well as the ratio changes chains or gears, I have a couple of 18" drop boxes on the shelf I might part with.
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kidturbo (11-04-2020)
11-04-2020, 03:11 PM
#954
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I use straith Asd8,s on my 40 outlaw , and use the zf boxes to switch propshaft direction , the zf ,s can turn full power ahead or reverse , my boxes cant take the power the duramaxes are producing . The Dropbox Arneson might be the best thing if the trannies can only transfer power the direction the crank is turning . My outlaw is Only running 64 mph With the 440 Yanmars , the duramax outlaw have so much more power that it probably can run in the 80,s but what will happen with the Arnesons pushing the stern up at those speeds , since there are no steps / rocker in the hull ? The inner lifting strakes stop at aprox 10 ft from the transom , but that is the only build in part that allows the rear part of the boat to sit down a little more . This can lead to bow steer ,sure the props can be tweaked for more bow lift , and correct prop direction will help too , but is it enough ? Those hulls need bowlift , and positive trim will help tremendous, and that is what an Arneson cant do .
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2187 (11-07-2020), bulletbob (11-07-2020), hogie roll (11-05-2020), kidturbo (11-04-2020), Twin O/B Sonic (11-05-2020)
11-04-2020, 10:26 PM
#955
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Thread Starter
Stirling pretty well sums it up.
Right now at 75-80 it carries the bow pretty nicely once you get past that porpoise. However that's also about same high trim when it cracked those lowers. So the question of thrust angle vs shaft load direction certainly comes back into play. I've also purposely been probing the turning radius at speeds for stability. Since it's current happy planning / operating speed is always above 45mph, need to be certain it doesn't have any prop walk tendencies with the current height and rotation. So far so good on that, and no chin walk noted either. IF we had to change drives, I'd have to say Merc's are the only reasonable option at this point in time. We could reuse the existing extension boxes, and not change the overall geometry. If ya recall, we set a 2.5* down angle on the powertrain.
Speaking of handling, I never really got a chance to play with the longer Kplanes.. Props broke loose easier we noticed, but she only got on plane twice before the gearbox let go. I think they worked, boat felt better coming up at least.
I have much of the hardware collected, and about ready to head back to FL. Time to get back on the other little jobs. Adding external reservoirs and some electric lift pumps to the dropbox oiling system. If it runs out of oil again, I little gnome will actually pop out of the hatch, run up and turn off the ignition key automatically... Besides that, we'll just Send It again.
Right now at 75-80 it carries the bow pretty nicely once you get past that porpoise. However that's also about same high trim when it cracked those lowers. So the question of thrust angle vs shaft load direction certainly comes back into play. I've also purposely been probing the turning radius at speeds for stability. Since it's current happy planning / operating speed is always above 45mph, need to be certain it doesn't have any prop walk tendencies with the current height and rotation. So far so good on that, and no chin walk noted either. IF we had to change drives, I'd have to say Merc's are the only reasonable option at this point in time. We could reuse the existing extension boxes, and not change the overall geometry. If ya recall, we set a 2.5* down angle on the powertrain.
Speaking of handling, I never really got a chance to play with the longer Kplanes.. Props broke loose easier we noticed, but she only got on plane twice before the gearbox let go. I think they worked, boat felt better coming up at least.
I have much of the hardware collected, and about ready to head back to FL. Time to get back on the other little jobs. Adding external reservoirs and some electric lift pumps to the dropbox oiling system. If it runs out of oil again, I little gnome will actually pop out of the hatch, run up and turn off the ignition key automatically... Besides that, we'll just Send It again.
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2187 (11-07-2020)
11-06-2020, 11:28 AM
#956
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Baja
I also remember Tyson having problems with his propellers on his V bottem with cummins engines , and arnesons , Had sheared off blades on several props , finally had them cnc cut out of steel , this must be something to do with the low rev cummins making a lot of torque down low , and the ratio that forced him using high pitch props, its something to keep in mind ... Decades ago when there was Hot boat magazine , and no internet in Europe ... there was a 31 ft cat , not remember what is was , think a Chris craft or a derisive from that , with yanmar 440,s and bravo drives , they mentioned something about bending the blades on the bravo 1 props under full torque , Searched all my old magazines through , but I never found it again ... this was in my single outboard years , where the inboards were far away from my wallet 😁
11-06-2020, 12:05 PM
#957
Registered
Stirling pretty well sums it up.
Right now at 75-80 it carries the bow pretty nicely once you get past that porpoise. However that's also about same high trim when it cracked those lowers. So the question of thrust angle vs shaft load direction certainly comes back into play. I've also purposely been probing the turning radius at speeds for stability. Since it's current happy planning / operating speed is always above 45mph, need to be certain it doesn't have any prop walk tendencies with the current height and rotation. So far so good on that, and no chin walk noted either. IF we had to change drives, I'd have to say Merc's are the only reasonable option at this point in time. We could reuse the existing extension boxes, and not change the overall geometry. If ya recall, we set a 2.5* down angle on the powertrain.
Speaking of handling, I never really got a chance to play with the longer Kplanes.. Props broke loose easier we noticed, but she only got on plane twice before the gearbox let go. I think they worked, boat felt better coming up at least.
I have much of the hardware collected, and about ready to head back to FL. Time to get back on the other little jobs. Adding external reservoirs and some electric lift pumps to the dropbox oiling system. If it runs out of oil again, I little gnome will actually pop out of the hatch, run up and turn off the ignition key automatically... Besides that, we'll just Send It again.
Right now at 75-80 it carries the bow pretty nicely once you get past that porpoise. However that's also about same high trim when it cracked those lowers. So the question of thrust angle vs shaft load direction certainly comes back into play. I've also purposely been probing the turning radius at speeds for stability. Since it's current happy planning / operating speed is always above 45mph, need to be certain it doesn't have any prop walk tendencies with the current height and rotation. So far so good on that, and no chin walk noted either. IF we had to change drives, I'd have to say Merc's are the only reasonable option at this point in time. We could reuse the existing extension boxes, and not change the overall geometry. If ya recall, we set a 2.5* down angle on the powertrain.
Speaking of handling, I never really got a chance to play with the longer Kplanes.. Props broke loose easier we noticed, but she only got on plane twice before the gearbox let go. I think they worked, boat felt better coming up at least.
I have much of the hardware collected, and about ready to head back to FL. Time to get back on the other little jobs. Adding external reservoirs and some electric lift pumps to the dropbox oiling system. If it runs out of oil again, I little gnome will actually pop out of the hatch, run up and turn off the ignition key automatically... Besides that, we'll just Send It again.
11-06-2020, 09:32 PM
#958
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Thread Starter
Keep up the fight!
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