1/2A OPC?? :^)

[nuzum]

I think Rod is a better guitar player than a machinist ....not bad at either Tho !

 

[Geraghty]

I still think the gearing loss may be a problem,

Lohring Miller

We thought that would be a problem also until David built the gearbox and we tested it.......The gearbox was built 8 years ago when all we had were a good selection .21 props to play with...

The smaller diameter props used in FE applications today did not exist.....The best we can figure out is slowing the prop speed down not only increased the torque of the motor output but the

increased prop efficiency because of the decreased prop rpm far outweighed the parasitic drag loss in the gearbox.....at least that is our story and we are stickin' to it....LOLOLOL

All we knew for sure is it really worked well on a reasonably heavy boat.....

 

[Ronald van Essen]

I dug up some pics for inspiration. Darin you could do something like Chris Fine.

Looks like a Bob Kensill boat plus geared motor

Here are the photos of the .12 tunnel/motor/gearbox combo that currently holds the IMPBA SAW record....

We have a new boat that this motor will go on to eventually assault the .12 tunnel 2-lap record....

Isn't that an old boat from Tommy Lee?????

I hope the guys are going further this way of geared setups, quite interesting stuff

 

[RonShaw]

I still think the gearing loss may be a problem,

Lohring Miller

We thought that would be a problem also until David built the gearbox and we tested it.......The gearbox was built 8 years ago when all we had were a good selection .21 props to play with...The smaller diameter props used in FE applications today did not exist.....The best we can figure out is slowing the prop speed down not only increased the torque of the motor output but the

increased prop efficiency because of the decreased prop rpm far outweighed the parasitic drag loss in the gearbox.....at least that is our story and we are stickin' to it....LOLOLOL

All we knew for sure is it really worked well on a reasonably heavy boat.....

Rod,

Did you have to do a lot of prop testing? I would think that by the way David setup the gear ratios that you would have more torque as well and be able to spin close to a 20 sized prop in the 38mm range. What range and prop did you end up turning? Did you or David have to do anything additional to the prop? This is a very interesting thread. Thanks.

 

[Geraghty]

Isn't that an old boat from Tommy Lee?????

I hope the guys are going further this way of geared setups, quite interesting stuff

Yes it is....This boat was built in 1996 for the Sport .21 class at the Ft.Wayne Internats.....

Tommy ran the boat for a couple of years and it suffered several wrecks.I have put the boat back together a couple of times....hence its increase in weight over the years.

When Tommy retired he gave me the boat and it sat on my shelf with a K&B 21 until 2006 strictly for display...When the .12 outboard project

came along,David and I thought this would be a good boat for that effort.I gave the boat to David Hall and it came out of retirement... The boat currently is sitting on a shelf in Hoover Alabama just

waiting to be called back into service.....

 

[Geraghty]

I still think the gearing loss may be a problem,

Lohring Miller

We thought that would be a problem also until David built the gearbox and we tested it.......The gearbox was built 8 years ago when all we had were a good selection .21 props to play with...The smaller diameter props used in FE applications today did not exist.....The best we can figure out is slowing the prop speed down not only increased the torque of the motor output but the

increased prop efficiency because of the decreased prop rpm far outweighed the parasitic drag loss in the gearbox.....at least that is our story and we are stickin' to it....LOLOLOL

All we knew for sure is it really worked well on a reasonably heavy boat.....

Rod,

Did you have to do a lot of prop testing? I would think that by the way David setup the gear ratios that you would have more torque as well and be able to spin close to a 20 sized prop in the 38mm range. What range and prop did you end up turning? Did you or David have to do anything additional to the prop? This is a very interesting thread. Thanks.

I built the lower unit and motor mount and rigged the boat...I then sent the boat to David and he built the motor.The first time he tested the boat it ran 50 MPH

with a standard 38MM 1440 with 2.3" cup Sport21 prop.......The record at that time was as I recall 38mph so we really had that covered....David put the boat away and took it to the next time trials in Huntsville....

First run he set the current record and put the boat back in the car..David might have tested it once after that but I just don't recall.... I do know it is currently sitting in beautiful downtown Hoover Alabama waiting for the next

chapter in its 18 years of service to the outboard gods....

 

[lohring]

We did a little work with gearing to match motor rpm to the available props. In this case we were gearing up from the motor rpm with a quick change gear box. You would need to cut the gears to make the tiny quick change gears for this application.

Lohring Miller

 

[Geraghty]

We did a little work with gearing to match motor rpm to the available props. In this case we were gearing up from the motor rpm with a quick change gear box. You would need to cut the gears to make the tiny quick change gears for this application.

Lohring Miller

Mike and Mark Change Gears.jpg

We considered doing that but the gear centerlines have to remain constant and there wasn't enough of a gear selection to make this viable,

and as long as Stock Drive Products was in business,this boy wasn't cutting any gears....

Our gear reduction selection was made by the SWAG [scientific wild ass guess]estimate system and it worked out pretty well...

Now is this the optimum ratio???...we don't have a clue....we just threw this ratio against the wall and it stuck well enough to set the record....

.....

 

[RonShaw]

I still think the gearing loss may be a problem,

Lohring Miller

We thought that would be a problem also until David built the gearbox and we tested it.......The gearbox was built 8 years ago when all we had were a good selection .21 props to play with...The smaller diameter props used in FE applications today did not exist.....The best we can figure out is slowing the prop speed down not only increased the torque of the motor output but the

increased prop efficiency because of the decreased prop rpm far outweighed the parasitic drag loss in the gearbox.....at least that is our story and we are stickin' to it....LOLOLOL

All we knew for sure is it really worked well on a reasonably heavy boat.....

Rod,Did you have to do a lot of prop testing? I would think that by the way David setup the gear ratios that you would have more torque as well and be able to spin close to a 20 sized prop in the 38mm range. What range and prop did you end up turning? Did you or David have to do anything additional to the prop? This is a very interesting thread. Thanks.

I built the lower unit and motor mount and rigged the boat...I then sent the boat to David and he built the motor.The first time he tested the boat it ran 50 MPH with a standard 38MM 1440 with 2.3" cup Sport21 prop.......The record at that time was as I recall 38mph so we really had that covered....David put the boat away and took it to the next time trials in Huntsville....

First run he set the current record and put the boat back in the car..David might have tested it once after that but I just don't recall.... I do know it is currently sitting in beautiful downtown Hoover Alabama waiting for the next

chapter in its 18 years of service to the outboard gods....

That's about what I figured. 38mm with a 12 engine sounds like the geared unit was working very well. Did you and David do your own custom prop work or did you have someone supply you with props to try? That was quite an accomplishment upping the record 12mph+.

 

[Geraghty]

I still think the gearing loss may be a problem,

Lohring Miller

We thought that would be a problem also until David built the gearbox and we tested it.......The gearbox was built 8 years ago when all we had were a good selection .21 props to play with...The smaller diameter props used in FE applications today did not exist.....The best we can figure out is slowing the prop speed down not only increased the torque of the motor output but the

increased prop efficiency because of the decreased prop rpm far outweighed the parasitic drag loss in the gearbox.....at least that is our story and we are stickin' to it....LOLOLOL

All we knew for sure is it really worked well on a reasonably heavy boat.....

Rod,Did you have to do a lot of prop testing? I would think that by the way David setup the gear ratios that you would have more torque as well and be able to spin close to a 20 sized prop in the 38mm range. What range and prop did you end up turning? Did you or David have to do anything additional to the prop? This is a very interesting thread. Thanks.

I built the lower unit and motor mount and rigged the boat...I then sent the boat to David and he built the motor.The first time he tested the boat it ran 50 MPH with a standard 38MM 1440 with 2.3" cup Sport21 prop.......The record at that time was as I recall 38mph so we really had that covered....David put the boat away and took it to the next time trials in Huntsville....

First run he set the current record and put the boat back in the car..David might have tested it once after that but I just don't recall.... I do know it is currently sitting in beautiful downtown Hoover Alabama waiting for the next

chapter in its 18 years of service to the outboard gods....

That's about what I figured. 38mm with a 12 engine sounds like the geared unit was working very well. Did you and David do your own custom prop work or did you have someone supply you with props to try? That was quite an accomplishment upping the record 12mph+.

I think Tommy did that prop....It was a very generic 1440,back cut 15 degrees and cupped to 2.2....

 

[Carl Van Houten]

If I am not mistaken I made that prop for David at our test pond. I spent about three hours on it all total and then he just about cut his dang finger off with it in Huntsville. It was sharp now...ask David.

That cut was TO THE BONE! Real nasty... he went to the E.R. and then came back and finished running the boat. NOW THAT IS A TRUE BOATER RIGHT THERE! It was a damaged 1440 to start with. I still have the final specs in my prop book.

-Carl

 

[RonShaw]

Carl,

Why am I not surprised you had a hand in that record? Awesome story. Thanks for sharing. That's a team effort for sure!!!

 

[RonShaw]

.

 

[Ronald van Essen]

Carl,

Why am I not surprised you had a hand in that record? Awesome story. Thanks for sharing. That's a team effort for sure!!!

I agree.

And thanks Rod for sharing some info on that boat.....sweet home Alabama...

 

[Geraghty]

If I am not mistaken I made that prop for David at our test pond. I spent about three hours on it all total and then he just about cut his dang finger off with it in Huntsville. It was sharp now...ask David.

That cut was TO THE BONE! Real nasty... he went to the E.R. and then came back and finished running the boat. NOW THAT IS A TRUE BOATER RIGHT THERE! It was a damaged 1440 to start with. I still have the final specs in my prop book.

-Carl

I do now recall that Carl did a prop for the 12 boat and David trying to amputate a finger

.....I had forgotten that bit of info about the boats history.....Memory slowly coming back...

I had also built a one off squarewave pipe for the 12 boat and David lost it at the same test session.....I had to build another for the record effort.....

There is still something missing in my memory RAM about the prop/pipe/testing session.....I will ask David and get back to you all......this reminiscing about the 12 tunnel is a hoot....

 

[lohring]

We did a little work with gearing to match motor rpm to the available props. In this case we were gearing up from the motor rpm with a quick change gear box. You would need to cut the gears to make the tiny quick change gears for this application.

Lohring Miller

Mike and Mark Change Gears.jpg

We considered doing that but the gear centerlines have to remain constant and there wasn't enough of a gear selection to make this viable,

and as long as Stock Drive Products was in business,this boy wasn't cutting any gears....

Our gear reduction selection was made by the SWAG [scientific wild ass guess]estimate system and it worked out pretty well...

Now is this the optimum ratio???...we don't have a clue....we just threw this ratio against the wall and it stuck well enough to set the record....

.....

I'm with you. It's always cheaper to machine available things with your credit card. However, the full size quick change gears were low cost. It would take some work, but might be worth it. Mike Bontoft built the full size gear box, and I once machined a set of change gears for a table top lathe.

Lohring Miller

 

[twox45]

Hopefully this will work. I have never posted a link to youtube before. We are in the process of putting ceramic bearings in the gear box, have upgraded to hardened gears for both (less drag). Martin has offered to put some good new numbers on a new powerhead. Also just finished drawing up a 24" outrigger hydro. We are shooting for 80 mph.

Well it didn't work so I just woke Rod up and ask him to post.

David

 

[Geraghty]

Hopefully this will work. I have never posted a link to youtube before. We are in the process of putting ceramic bearings in the gear box, have upgraded to hardened gears for both (less drag). Martin has offered to put some good new numbers on a new powerhead. Also just finished drawing up a 24" outrigger hydro. We are shooting for 80 mph.

Well it didn't work so I just woke Rod up and ask him to post.

David

 

[kesso2118]

That is one sweet sounding little boat

 

[Matt Mordja]

Very nice guys...