Thinking about a new design

**Papee** · 04-03-2011, 12:40 PM

I"ll try to explain it. Unfortunately most do not understand "Papee talk".

First of all it would be chain drive using 4 wheeler sprockets and chain. It would be a relatively "quick change" gear box. It would be inclosed and have a bathe keeping the parts oiled. It would have a "tub" at the bottom where the lubrication(chain saw oil) would be with a removable cover to change the sprockets and chain.

The hub would be drilled and tapped for easy change of gearing. This would not have a starter attached to it and is pretty much specific to my application.

Discuss?

**n4wsp** · 04-03-2011, 02:04 PM

I think it would work. Maby a 428 or 530 motorcycle chain. that is the way the Harley primary works.
Steve

**buster** · 04-03-2011, 06:08 PM

Papee,

Sounds to me like it would be a good setup, but I wonder if you actually need an oil bath? Roller chain doesn't usually require that much lubrication. I would think a couple squirts with an oil can every week or two should be adequate.

Dave

**Duane Scarborough** · 04-03-2011, 06:37 PM

Originally Posted by Papee

I"ll try to explain it. Unfortunately most do not understand "Papee talk".

First of all it would be chain drive using 4 wheeler sprockets and chain. It would be a relatively "quick change" gear box. It would be inclosed and have a bathe keeping the parts oiled. It would have a "tub" at the bottom where the lubrication(chain saw oil) would be with a removable cover to change the sprockets and chain.

The hub would be drilled and tapped for easy change of gearing. This would not have a starter attached to it and is pretty much specific to my application.

Discuss?

Papee,

I am not familiar with "4 wheeler sprockets and chain". Is that regular roller chain?

Early on, I thought about something similar, using automotive camshaft timing chain. But I ran across the Arrow Prop belt drive, and didn't look into it any more.

I have ran a lot of motorcycles in the past, with single roller chain final drives. These were all open, and a shot of spray chain lube every now and then seemed to take care of them.

So it "may" work OK.

Duane

**n4wsp** · 04-03-2011, 07:06 PM

Most new motorcycle chain is pre lubed and has o-ring's between the plate's and roller's only very little chain lube is needed
Steve

**Papee** · 04-04-2011, 10:57 AM

I suppose if they have the o rings in it wouldn't be good to have too much oil on them. I just figured since I was enclosing the chain I would oil it. I'm going to make the case a bit oversized in case the chain breaks so it don't get jammed up between the sprocket and the case. I do want to enclose it so the chain don't go into the prop. I'm going to make one for the 032 I have first and bench test it before going to the 084.

**Flathead** · 04-04-2011, 01:54 PM

Papee,

Leave lots of room in the case for the chain. In a snowmobile when the chain breaks in the chaincase it folds up on itself and quite literally explodes the case. It has nowhere to go. Happened to me this winter. not a pretty sight.....

Flathead.

**n4wsp** · 04-04-2011, 02:16 PM

I don't think you will ever brake a 530 motor cycle chain. I have jerked them up and down the drag strip all my life with some powerful drag bike's never broke one.Just make sure you put the master link clip on with the closed end in the direction the chane travels.

**Duane Scarborough** · 04-04-2011, 06:39 PM

Originally Posted by n4wsp

I don't think you will ever brake a 530 motor cycle chain. I have jerked them up and down the drag strip all my life with some powerful drag bike's never broke one.Just make sure you put the master link clip on with the closed end in the direction the chane travels.

A very good point Steve.

I've seen some pretty nasty results from a master link clip put on the wrong way. I've never seen a 530 chain break, but I have seen them come apart at the master link. When asked, they always said something like "You mean it makes a difference which way you put the master link clip on?"

You also make a good point Papee. A broken chain would not be what you wanted to go thru a prop. (I hadn't thought about that.)

But like Steve said, there ain't much chance you'll break a 530 motor cycle chain, at least not with a 45 HP engine.

You may be better off to leave it open, so that you can easily inspect it, and shoot a shot of chain lube on it occasionally. Sealed chain is good at lubricating the bushings/links of the chain. But that doesn't do anything for the chain to sprocket wear.

Duane

**Papee** · 04-05-2011, 07:58 AM

Now that I'm not going to do an oil bath I can just attach the bottom of the cover with 4-6 screws and it will be easy to take the plate off to inspect or oil the chain. I'd rather have it covered, just one of my phobias. I've seen/had a prop explode when I hit the tree that time, it aint pretty.

**eskimoboy** · 04-05-2011, 01:07 PM

Hey Papee do you think building this chain reduction would be cheaper than buying a reduction unit from Arrow Prop?
You are also getting a top speed with direct drive of 38MPH is that in deep or shallow water?
With this reduction what increase in MPH do you expect to obtain.
Thanks
Nick

**Duane Scarborough** · 04-05-2011, 07:46 PM

Originally Posted by Papee

Now that I'm not going to do an oil bath I can just attach the bottom of the cover with 4-6 screws and it will be easy to take the plate off to inspect or oil the change. I'd rather have it covered, just one of my phobias. I've seen/had a prop explode when I hit the tree that time, it aint pretty.

Papee,

Phobia? Yeah, maybe that's the right term.

But I also understand what you mean. Anything going thru the prop would be bad. A chain going thru the prop could be REALLY bad.

Maybe if you used expanded metal? That'd contain the chain if it ever did break, but you'd be more likely to inspect/lube it that way.

It's just a thought...

Duane

**Papee** · 04-05-2011, 08:34 PM

Originally Posted by eskimoboy

Hey Papee do you think building this chain reduction would be cheaper than buying a reduction unit from Arrow Prop?
You are also getting a top speed with direct drive of 38MPH is that in deep or shallow water?
With this reduction what increase in MPH do you expect to obtain.
Thanks
Nick

I doubt the cost would be much cheaper because of having the hub machined and the cost of the enclosed chain.
Top speed? It depends on what you call shallow water. I was in about 2 feet of water when I hit that speed and had my boat stripped. My boat is also a flat bottom boat, no chines. I'm not really looking for more speed, just a better cruising speed at a comfortable rpm of around 3400. My cruise rpm is about 3000 rpm and 25 mph now, I'm not sure what will change with the new round of deck mods to my boat. I'm really just looking to recover what I will lose with the extra weight I have now.

**Papee** · 08-24-2013, 08:18 PM

Well I'm back on this idea for the 084, I need to think of something to get these boats spinning a bigger prop. Putting the ones availble on two boats now will be E X pensive. I really need to come up with something I can afford. Now that I have found out we have a machinist in the family I may get this figured out.

**Papee** · 09-09-2014, 12:43 AM

Since I finished a few projects and now only in the middle of fifteen or so I've decided to carry on with this one. I now have a reliable starter so I don't have to be concerned about incorporating it into the redrive. I've been laid up today after a fall in the boat the other day so I had plenty of computer time today. I have all the plans laid out in auto cad I just need to start collecting materials.

I will be using the stock flywheel and machining it down for the drive pulley/sprocket. It already has drilled and tapped mounting points. I may redesign this later if costs make it cheaper to produce that part from scratch. Using the chain drive makes it a simple task to convert the prop hub to chain drive. Some prop hubs already have a sprocket on them. These are made for a one inch shaft and I happen to have one left over from my boat when it had the opposed twin engine on it.

This will be great for me especially because the cage on my boat will not accept a larger prop. I can gear each reduction to the prop it needs easily by changing the tooth number on the upper sprocket. I'm just not a fan of belts and think this will be a less maintanence design than others before it. The design will use the two pulleys as the others have had along with a tensioner sprocket. The pressure on the tensioner sprocket will not have to be real excessive so chain stretching should be minimal.

This concept will allow me to use a smaller pulley/sprocket on the output shaft and also making the final drive sprocket smaller due to the sprockets having no slippage problems. This will allow me to make the unit smaller and lighter than others.

Ive ordered my materials and hope to get started as soon as I get the green boat back on the water after putting the new starter setup and intake and carb. I will have updates on this but there won't be too many photos of my progress. Due to using parts that are already available I'm hoping to keep the cost down making them more affordable along with the mini airboat concept.

Edit:
I am working with Don at Arrow props to design a prop specifically for the rpm range this reduction will be. I'll discuss this number at a later date.

**txriverrat** · 09-09-2014, 12:10 PM

Papee
In my younger days when I lived on the Texas coast a friend of my dad and about half outlaw had a small airboat.This boat was rigged for floundering,and in my feeble brain I think it was a 5 by 12 hull. He outran every game warden around .
He was running a wisconsin air cooled engine ,wood prop and a chain drive. It was a pretty simple set up as I remember it ,sprocket on the motor , a shaft mounted in two pillow block bearing with a larger sprocket on top and the prop mounted on the same shaft.
In the five years I knew him he was running 2 or 3 times a week and I dont remember him ever throwing a chain . Oh and the chain wasnt enclosed at all.
I do know a chain is more efficient than a belt and also easier on the rear bearings of the motor.
You may be on to something here.
Will be watching this with interest.
Ron

**Papee** · 09-09-2014, 05:36 PM

Yes with the chain you won't have as much lateral tension on the shaft because the chain won't need to be near as tight as a belt. All I need is more time to get this all done, I'd like to get this together real soon because its time for a new prop. Mine is getting bad.

**aerokirk** · 09-09-2014, 07:45 PM

I used a chain and sprocket drive with a sprocket idler when I made my ATV snowblower and it has worked flawlessly for years. I made a steel fulcrum for the idler sprocket and mounted the idler on one end with a pivot bolt in the center and a spring connected to the other end. This makes it self tensioning and nearly noiseless. The only issue is chain and sprocket wear unless you have an oil bath or are diligent about lubing the chain.

**Papee** · 09-09-2014, 08:25 PM

I really don't think the cost of replacing the chain and sprockets would be much more than belt replacement considering how much longer a chain and sprockets would last over a belt.

**Papee** · 02-07-2015, 12:07 PM

I'm finally in the process of getting the parts together for this. I am looking for sprockets that have a three bolt hole setup to mount or at least enough meat that this pattern can be added. The sprockets will be smaller than the ones used in the belt drive systems because there will be no slipping with the chain. The sprockets will also be relatively close together. I am shooting for around 1.6/1 ratio for the prototype setup, with this setup the gearing could be changed out in minutes just by changing the prop side sprocket.