Gears

[Grand_Marlin]

Why dont we have gears in boats? :D

Just imagine the fuel savings you would get if you could do 25 knots at 1500 revs.

Cheers

Pete

[backlash08]

space and weight would be against us Pete, variable hyd motors driving props would also be an option - cheers - Craig

[Roughasguts]

Yup an auto trans be worth a try!

[Roughasguts]

Clee, me old mans got a velvet drive in his boat that would be the size of a Auto trans I reckon. Mind you it's aluminium.

[Noelm]

I guess with some Engine design changes to alter the RPM range, and a two speed gear sytem up near the Powerhead (more weight up high, but no drag) we could have a couple of gears for different applications.

[Noelm]

how about we go for the tried and true variable pitch prop, surely in this day and age, someone could make one to suit high RPM applications, that way we could have an almost endless gearbox/ratio/drive

[Dean1]

You at home bored Pete ;D Ive thought about this before too mate, it doesnt seem right just havin 1 gear at times. Love my new f 60's mate, ill give you a call sometime soon see how your trip went. You should be gettin that 18' cat on the water theres snapper everywhere!!

[Blackened]

You should be gettin that 18' cat on the water theres snapper everywhere!!

G'day

I know!!!!!

Dave

[Grand_Marlin]

I have never been offered any help :(

[Blackened]

G'day

I'll do the detailing, and I've also heard dean will help you with sanding and grinding.... I hear he looks good in a sperm suit

Dave

[MarkDiver]

Why dont we have gears in boats? :D



Just imagine the fuel savings you would get if you could do 25 knots at 1500 revs.


Cheers


Pete



::) You need to keep one hand free to hold your beer, if you had a clutch and other stuff to contend with it would be too complicated ..keep it simple stupid :P LOL

[cormorant]

Manufacturers can hardly build a relaible lower unit now.

CVT would be good

There were several versions of 2 speed props that worked OK and were based on a set spring that could be adjusted and pitch adjuster to set max and min pitch. Good on a ski boat as they jumped out of the hole and as speed built and pressure on the hub / blades lessened the pitch would change and give you a better top end. Tourqe master or something from memory was the name - would have to check the shed - business died when manufacturing plant burnt 45 years ago from memory.

The biggest issue is always that it needs to be individualised set up for so many different boats and applications unlike planes where weight is the variable.

New technology with electrically activated metals and plastics may allow blade shapes to change to retain effeciency.

Should allow engines to be designed to run more effeciently at a particular rev and load range instead of the compromise we currently get from manufacturers of motors trying to be jack of all trades.

There was talk of the diesel outboards coming with a 2 speed box in the midsection so the hydrodynamics of the lower unit aren't lost and also dropping cylinders for low rev troll etc etc. Lots of ways to make things more effecient but much comes at a discount to reliability unless properly engineered.

See what the future brings and hope not to much of the past keeps repeating.

[walruss]

A mate has a ski racing boat. mid engined 350 chev with a v drive. runs through an old 2 speed hydromatic auto box.

Off the mark unbelievebaly quick, gets the revs up and slots into the next gear and just keeps going. Does well over the 160km/h.

Have no idea re fuel etc. But bloody quick!

Russ

[Roughasguts]

Hydromatic yep remember that G/B in a HT Holden with a 186 cid not much chop in a car, but the G/B be my choice for the boat.

[FNQCairns]

A mate has a ski racing boat. mid engined 350 chev with a v drive. runs through an old 2 speed hydromatic auto box.

Off the mark unbelievebaly quick, gets the revs up and slots into the next gear and just keeps going. Does well over the 160km/h.

Have no idea re fuel etc. But bloody quick!

Russ

Yes well that would do it! fit a prop that in high gear would lugg the rig by 20% at slow speeds, need good torque in the engine though.

cheers fnq

[tunaticer]

I think it would not take much to add a two speed gearbox immediately under the powerhead and drive the shaft at two different ratios. It would not take a whole lot of engineering to sort out. We could change the ratio in the forward reverse box in the leg to suit the variable speeds of the drive shaft. Technically it is not a huge obstacle to overcome, convincing outboard manufacturers thats its a wanted option would be much harder.

Jack.

[Dean1]

G'day

I'll do the detailing, and I've also heard dean will help you with sanding and grinding.... I hear he looks good in a sperm suit

Dave Ha ha yeah sounds like a plan :) Dave your so good at detailing I reckon she wouldnt even need a sand ey!! Just put the wax on a bit thicker mate but you mite have to borrow my sperm suit tho in case wax gets thrown around all over the show!!

[Spaniard_King]

Guys,

IMO it could be done but!!!! Engine power head design would need to change to a lower rpm engine. Most outboards acheive peak torque around 4000 rpm.

Remembering that manufacturers like there engine to be proped to acheive maximum rpm having a 2 speed box you will need to still be able to acheive maximum rpm in top gear or the engine would be concidered overloaded!! So in actual fact all that would be acheived would be a far superior hole shot than what we have now with it still coupled to the max rpm and speed for what a properly proped boat acheives now. Cruise and max speed would not change.. more HP is required to change cruise speed and maximum rpm .. that is unless the laws of engineering have changed :)

[FNQCairns]

Guys,

IMO it could be done but!!!! Engine power head design would need to change to a lower rpm engine. Most outboards acheive peak torque around 4000 rpm.

Remembering that manufacturers like there engine to be proped to acheive maximum rpm having a 2 speed box you will need to still be able to acheive maximum rpm in top gear or the engine would be concidered overloaded!! So in actual fact all that would be acheived would be a far superior hole shot than what we have now with it still coupled to the max rpm and speed for what a properly proped boat acheives now. Cruise and max speed would not change.. more HP is required to change cruise speed and maximum rpm .. that is unless the laws of engineering have changed :)

Hi gary, I agree with most of what you said although if the extra gearing allows the engine (when travelling as fast as it can go on the first gear ie max safe revs, 1st gear would be over rev-able) if changing gear at this point to the second gear where the hull water resistance is now at it's 1st gear least will drop the engine rpm back closer to it's maximum torque output rpm.

This would in effect be a second wind, as i said above it would need good torque and only a 20% change in ratio or even less I guess would depend how much of the hull was out of the water by the end of 1st gear rpm.

The faster the hull travels through the water the less hp it takes to push it due to increasing lift, if there was no lift in a boat hull I would agree with you completely.

cheers fnq

[Spaniard_King]

Yeh Scott, Un fotunately I don't think anyone will take up the challenge.

I met a colourfull fellow today, his name is Frank Wheeler do a google search on him.. came to drop his outboard off for some work.. 2 hrs later he left and I new most of his life story.. he's a rich eccentric inventor/explorer/debt collector...lol

[FNQCairns]

Yeh Scott, Un fotunately I don't think anyone will take up the challenge.

I met a colourfull fellow today, his name is Frank Wheeler do a google search on him.. came to drop his outboard off for some work.. 2 hrs later he left and I new most of his life story.. he's a rich eccentric inventor/explorer/debt collector...lol

Yeah eccentric works ok sometimes, was it a paddle-wheel outboard;D, one big spanner in the works is the frictional losses from the extra gearing, in practice a real hard ask but nice to throw it around, retractable wings might be a better option:)

cheers fnq

[cormorant]

Some links


http://www.aerostarmarine.com/ppp.html

http://www.torqueshift.aeromarine.com/

Mercury had a power 2 prop a few years ago - don't know what happened to them and they were also producing a 2 speed mercruiser leg as well in 1999.


As an example a 150hp motor at 3500RPM is possibly puting out as little as 100hp but you need the acceleration and power of the 150hp to get the boat over it's own bow wave and on the plane.. So if you could do this with a 100hp motor and a variable prop or gearbox you could have a smaller lighter more effecient motor still pushing your boat. Friction and the transition from displacement to planing is the big killer for boat motors and hence the way they are tuned.

There is no such thing as an effecient prop at anything but one speed at one loading as everything else outside that has more ineffeciencies.

Drag boats are sometimes running 2 spped transmissions.

[on-one]

here's one for volvo legs http://www.stepdrive.co.uk/

[John West]

how about we go for the tried and true variable pitch prop, surely in this day and age, someone could make one to suit high RPM applications, that way we could have an almost endless gearbox/ratio/drive

I reckon Noelm is on the money ,its akin to a propeller driven airplane, you don't see gearboxes on planes.

Someone just needs to design a decent variable pitch prop.

[TimiBoy]

Other options - VVT, Contra rotating props, forward facing props even, hmmm, seen that and liked it...

Many options out there for efficiency improvement.

Cheers,

Tim

[cormorant]

Don't forget the caterpillar drive from Red October - Yes Captain - start the caterpillar drive in Russian accent - duuuuuuuunnnnp.................duuuuuuuuuunppp.... ......................duuuuuuuuuunp add whale song on speed here!!!!


I know the 2 speed props were about $ 1200 each and all had problems with high HP applications and wear. Ski boats on a river OK but it has to be a high constant speed offshore boat to justify offshore.

I expect everything in n amercruiser box not to last long ( if stored in the water) so I wonder if that one is an original volvo mercruiser or and sftermaket one? I like that in different sea conditions you can change the change point.

[Dirtysanchez]

CVT is pretty much the concept they use in them annoying scooters the Cafe Latte boys ride around the traps nowdays, you could modify / restrict this to just a couple of set diameters so you essentially have a sequential ratio over 2 gears.
I used to have a mate with the Hydromatic gearbox in his ski boat, and it went hard, in fact I am wondering if thats the reason behind my thinning hair ?

[ScottB]

As Cormorant said, Mercruiser had a two speed system a few years ago, the gearbox was situated in the boat between the engine and leg and was only available on diesels from memory, seemed lke one of those great ideas that never really took off.

Scott