Boat clutch

old roto tiller mechanism

>>1152525
like a slip clutch?

how would I DIY that?

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Thats how a mower deck works.
The drive belt (at least on mine) is similar but with 2 pullies that pivot together on an assembly to tighten the belt. A spring puts the tension on the belt and the clutch disengages (streches) the spring to remove the tension

You don't need a clutch in a boat, at idling speed of 9hp there won't be enough torque to move your boat.

>>1152533
my motor has an electric start, and I don't wanna burn it out, turning over the engine, AND the prop in the water. but if you could convince me otherwise...

>>1152531
this is where I got the idea actually..
what I was going to do was have my throttle [hand lever push forward kind.] hooked up to a secondary "lever" just below it, and after say the throttle gets pushed up 1/8th the way to full or something like that, it also starts to push up the secondary lever [without me having to manually touch the secondary lever] the lever pulls on a cable that goes to the engine that pulls the idler pulley into the drive belt to engage the prop. as I let off the throttle the pulley comes back up right before the engine hits idle.. sounds complicated as hell, but I assure myself, its 2 steel plates, some bolts an nuts, and 2 cables for engine throttle and pulley engagement.

>>1152536
Well the engine would be turning over regardless of whether you had the clutch in, it would just use a little more fuel, or stall it if it's gruntless enough. That's quite a cool sounding lever mechanism, I guess this isn't with an outboard motor. Is there room for a belt system / extra wheels in the existing belt system? I'm quite interested.

>>1152548
Its just a converted lawn mower engine I got for free. I already cut new oil ports and plugged old ones and put in an oil flicker. And yeah there is plenty of room for extra stuff. The boat atm is just a frame, I'm building the boat half myself as well. But that I don't need any help with as its not my first..

The boat is 8 feet long. The "engine box" the part where all the mechanical bits will go is 2 in a half feet long and about 4 feet wide. Shoot over your ideas. I may do them if they are feasible and aren't gonna rob me too much useable moving power.

When I'm done with my shower ill get on sketchup and do a 3d drawing of the lever mech idea. And post it here so if people wanna see how it works or just save an possibly copy the idea later thats fine with me. >>1152548

>>1152522
I would make the clutchroll on the other side, because in your drawing it is on the pull side.

>>1152553
A problem with this is you'll need to be able to move the second lever with enough force to engage the wheel onto the belt. If you want to take your hand off the throttle, this sin't going to happen with a direct mechanical linkage. You'll want the clutch to latch once you push the throttle lever past it's minimum rev point, and detach once you bring it back below that limit. Done well, there wouldn't be any extra force on the lever even when idling, just when you push past that threshold. For this force to be as little and short as possible, there needs to be the lowest displacement possible between the moving wheel being engaged to not being engaged. I'd suggest having the two static wheels on either side of it as close together as possible so that minimal tensioning is needed by the dynamic wheel. For the latching mechanism I'd suggest something with a strong detent akin to a large toggle switch. If you get something like that with two "switch handles" then you could have a small extension beneath the throttle's fulcrum and have that switch one handle when pushed past the rev limit, and switch the other one back when pushed the other way.

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Alright here it is. First version

>>1152568
I thought about that while in the shower. I had some mechanical ideas on how to accomplish it, but they all seemed over complicated for something so simple.

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>>1152574
Can't EDIT REEEEEEEEEEEE
Maybe there is a way I could push the lever a firm CLICK forward [furthermost point forward] and that disengages the clutch, but then id have a really wild running motor for a second.. so maybe not such a good idea. Something im trying to avoid is a "air plane throttle" type system, with 2 levers next to each other, one you just tap back a notch to "engage" the clutch, and the other is completely throttle control.

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>>1152522
>the simplest

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>>1152522
>so will this work, Black pulleys [top one idler] red belt, I just need to pull a lever to engage the idler and put tension, causing the other pulley [prop shaft] to start spinning with the motor.
Yes, it works.
In fact two of the most popular models of light helicopter are clutched that way (pic related). They don't leave the engine running with the clutch disengaged for very long though. It's engaged within seconds of starting the engine and disengaged 30 seconds before shutdown.

>>1152625
The problem with that sort of clutch would be less how long it's left on for, and more with how many times it's engaged/disengaged, because that's where friction wears the belt down the most. With a boat you're hardly going to be changing gears or whatever, so just leaving it in an idling state is almost certainly fine. Anything without multiple gears, like a ride-on mower or helicopter, can benefit from this sort of simplistic design, so long as their clutch isn't engaged often.

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>>1152522
can be even simpler OP

>>1152723
Thanks but pulley 1 is connected to the engine shaft. And pulley 2 is connected to the prop shaft. Both are static.
>>1152615
The motor has to be inboard because of a couple of reasons. One being noise. It is an ex lawn mower engine (4 stroke) and its pretty noisy.


Another thing I've been thinking about is the engine cooling. Since its enclosed mostly because of sound, I'm having ducting that will blow air across a scoop and down into the box across the engine then another cutout out the back of the boat for the hot air to exit. Another idea was to have a water pump on the pulley setup and it would pump the outside water inside the boat, through hard copper lines, that I bent up and around the fins of the cylinder and also drill some holes in the bottom of the crank case and ran some lines through where the oil will sit. The water would be pumping whenever the engine was running. But obviously if I don't have a cooling problem with version one aircooled. Then I won't even bother doing any of that.

>>1152741
how are you going to deal with not having a thrust bearing?

and where are you getting the propshaft, stern tube, gland nuts, propeller and rudder from for less than the cost of an outboard?

>>1152768
>and where are you getting the propshaft
Probably a gokart axle or something I have laying around.
>stern tube
Probably just a mild steel pipe or if I can find the right plastic like nylon or something in tube form.
>gland nuts
Why would I need them?
>propeller
Gonna have to buy that probably but I'm just gonna get a plastic one at first because I'm insure of the size and pitch, I know its gonna be a fairly small diameter and two fin with a fairly medium range pitch to get started.
>rudder
Going to build it from wood, nothing a few lines, a hand saw, and a number 7 and number 4 plane can't handle.
from for less than the cost of an outboard?
Idk where you live that you think boating motors are cheap. But the irony doesn't escape my humor. Good joke newfriend.

So far my total invest me in money on this whole build is exactly 8 dollars...

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>>1152781
>gland nuts
>Why would I need them?
wew lad

>>1152827
Nothing a little silicon-carne can't fix.

>>1152827
Still haven't explained why I would need one... If you're talking about the use of them in a bung hole. I don't use that style for my boats. I store my boats upside down so the drains are at the topside.

>>1152966
Where does the propshaft exit the boat and why will water not go through that hole?

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>>1153080
No, as long as there is a bushing of some sort, with a tight tolerance around the shaft that is enough to keep the water out, there is fancy ways of doing it, but this is by far the simplest. a more advanced way I've considered.
INSIDE BOAT | standard bearing | 1" thick plastic bushing/ring tight fit around the shaft | sealed bearing | OUTSIDE BOAT

doing some research online today, haven't really put any more work into actual design today, came across this link below, and this cringe worthy floating platform... [pic related] someone was actually proud of it an put it on the internet.. I've built some crap in my day... but shitting up others nice views with your crap, that's just wrong.

and here's the pretty cool link.
http://www.gutenberg.org/files/41669/41669-h/41669-h.htm

>>1152781
A thrust bearing was mentioned.

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>>1153085
I've always wondered why boat people invent weird thinks like grease-sealed bushings or water bearings. Can't you just use one of these? They're super cheap and of every possible dimension.
Otherwise it's nice idea, I would go with several springs bistable mechanism that would engage/disengage the idler in one quick motion, avoiding unnecessary wear on belt.

>>1152522
Just get a lovejoy coupler or some old u joints

>>1153150
>lovejoy coupler
How would I set that up?

>>1153097
Yeah.. I don't understand it really either. Those things can hold out several bar worth of oil pressure and heat (seen them in engines most of the time) but cant hold out water?

Google image search: Thailand boat engine

Just lift the prop out of the water. Put a good muffler on the thing if its noisey.

>>1153298
The muffler isn't the issue. I already have a packed muffler on it. The cylinder walls are just freaking thin. So you get a lot of valve noise with piston.

>>1153085
Those bikes are going to rust the fuck out.

>>1153097

Because water is a bitch and finds its way through the packing no matter what you do.

OP, invest in a sump pump of some sort, you'll need it.

>>1154334
I got a cheap 12v battery powered one.

No further updates yet. Probably going to work on it today

>>1153275
2 pillow blocks on a shaft. Put love joy ends on motor and shaft. But them together

>>1153085
>>1153097
The reason most inboards use a grease packed stuffing box is because holding any sort of a tight clearance on any component outside of the engine is near fucking impossible to do.

Boats, at least larger ones, usually have a significant amount of flexing in pretty much all components, when you combine this with the wear of the prop shaft or surrounding material, corrosion and shitty maintenance you get a situation where you could be looking at a huge range of tolerances that would make using any sort of static seal difficult or impossible. The beauty of the stuffing box, specifically the old grease stuffed twine type, is that you can easily change the degree of pressure on the prop shaft, if it wears or something else happens, you just torque it down a little more, corrosion starts to take hold, loosen it a little bit until it works itself out.

The only negative is that the seal is at adequate pressure while underway ,(warm), if there's a significant temperature change it usually leaks a little bit, that's why most boats that are stored wet will have an automatic bilge pump.

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>>1152522
>I'm going for the cheapest solution that just gets me out on the water with no fuss.
here you go op

>>1152533

If the prop is spinning, which it will be if there is no clutch and the engine is running, the boat's going to move.

The boat weighs almost nothing, FFS. I can (slowly) push a boat, loaded, weighing well over 10x that weight, and it doesn't take much effort, either.

>>1156254

I have no idea how new you are to boating, OP, but you may want to seriously consider just using an oar or two. By far the simplest thing, it's really not much effort in still or slow water (especially with a small, light boat), and it keeps the peace and quiet.

Personally, I'd ditch the engine in favor of the oar. Especially considering you're going to want to keep one on board, anyway, in case the engine shits itself on the water.

>>1156256
Nah. I'm not new to boating. And paddling sucks. When all you want to do is relax. Sorry my idea of relaxing isn't working my ass off to paddle 2 miles up a river. I built a skin on frame canoe. Paddled that for a while. Was okay on some days. But sucked when you got bullied by faggots on jetskis that wont fuck off. And paddling 30 minutes just to get away from their shit isn't that fun. Hence why I want something with just a good enough motor. Ive decided I'm going to go with about a 6 in a half so inch prop. And probably like a 2.4 inch pitch. Just gotta find or make the prop.. I know 6.5 sounds small. It is. But the motor is small too. And I'm going for light weight.

If anyone whos into RC maybe that would know where I could find 6 inch or bigger props do let me know please.

>>1156341
Pretty sure any RC boat with a prop that big would feel a reactionary torque from it, making it roll to one side.

OP just get a centrifugal clutch, I've never had a problem with one burning out, even on a motorcycle with high gearing. You are literally going to spend more time making a belt clutch then you will being able to enjoy yourself on your boat

>>1156458
Boats require the engines torque from the start.. No time or chance for the clutch to spin up to the required RPM for the plates to spread apart an engage. You want as much use able off the line power you can get. Especially when maybe your motor is running a low bare bones RPM to keep the flow of water from pushing you around. I really considered them. But I think they are gonna burn out too easily.

another day hounding Craigslist for a 10-20HP outboard. nuffin. or just ridiculous prices. for 30+ year old motors.

decided to see what 10horse power outboards cost new. I about fucking died.

OP ditch the inboard idea, its going to cause you a heap of headaches for no real gain over the outboard especially since you seem to be tighter than a fishes arsehole.

Go with the simple thailand model that has been mentioned previously. That way you can ditch the clutch completely and directly connect the prop shaft to the motor. You'll also have a much more positive steering solution too and remove the big hole in the boat hull that you won't be able to seal up effectively.

>Noise
Weld up an extension from the exhaust to that it vents into the water, this will dampen the exhaust noise dramatically. If you're still sensitive to the remaining engine noise, create an engine cover out of fibreglass or wood. Just leave some vents on top to allow the hot air to escape.

>Its still too noisy
Well you mention that jet skis use the same waterway so how the put-put of a small four stroke is louder than that is beyond me.

Just go with the KISS solution and you'll be able to spend way more time fishing.

>>1156832
the fuck you need 10hp for an 8ft boat?

>>1156832
I've got to ask where do you live?

Where I am, (Southeast VA), there's a huge fluctuation in the pricing of outboards and boats in general on craigslist/etc, right now is the worst possible time to buy, people still have some thought that they might use the boat/outboard and as such will usually only part with it for a higher price. The time you want to buy is right around Christmas or right after the end of the boating season for you. Outboards also are usually cheaper as you move inland try searching away from the coast, as an added bonus for this the outboard is apt to have never seen saltwater.

You ought to also consider that 30+ year old motors, provided they're still running, are pretty much bombproof, the usual life of an outboard owned by someone who doesn't care for it properly is usually around 15 years and the number one way outboards go is due to poor maintenance, If you can pick up a wrench and google creatively, working on older two stroke outboards shouldn't be an issue at all.

For reference, I own a 30hp 1984 Yamaha that I bought off of a guy for 250$ as a non running outboard, it wasn't seized and still had a spark so I figured it was a carb issue, a few bucks in gasket materials later and I've got a running outboard that's lasted me several years.

>>1156896
10hp is barely going to get me 10 knots m8. Hate to break it to ya.

>>1156995
Too bad. I live in florida. Everything you wrote is moot.. Boating season doesn't end, everyone thinks their junk is worth gold.

I don't have a problem working on the motor. But since boat motors are normally used around dirty and sandy areas. Its the cylinder walls being all fucked up that I care about. 250 dollars for a motor. Just to drop maybe 130 dollars at the machine shop to bore an hone the cylinder walls, then what ever ridiculous cost it is for a piston and rings, because MUH ITS A BOAT MOTOR EVERYTHING IS MARKED UP 500% of normal engines!

>>1157001
Yeah, dam, looking around the Miami area all of the prices are absurdly high, it's fairly common to see a non linear price/hp ratio as most people seem to want around 3-400 for everything.

The best I could say is just see if you can talk someone down by haggling over mechanical issues, or start looking a bit more to the north and take a road trip.

>>1157001
I get 8 knots with an 8hp on a 27ft, you must weigh a shitload

>>1157026
Wood hull boats tend to weigh more. Yeah.

>>1157009
Check the orlando/lakeland/tampa craigslist. Those are my stomping grounds. Lots of boats with no motors. But no motors for sale. You would think motors where consumable...

>>1157078
Yeah, looking around Orlando, the situation looks pretty much the same, most are horribly overpriced (relatively speaking), I'd be willing to bet it's just because summer is coming around. if you were to wait until the fall your apt to see some better deals come up.


I did just notice that your your boat is only 35lbs so I'm assuming it's some sort of kayak/solo canoe, in which case you can probably get away with a far less powerful outboard than you think, as long as your not trying to get over hull speed and onto a plane you shouldn't need much, medium sized sailboats can be pushed around with a 5-6 hp outboard at 6 knots with the right prop. I've also personally been in a 18 foot Royalex canoe with a 5hp outboard, with just two people in it, you could easily hit 10 knots which is about all I'd want in a medium sized river or creek.


If I were you I'd just scan craigslist and wait for something to come up, any sort of engine intended for land use is going to choke in a few years being around saltwater, and the costs are apt to be about the same in the end.

>>1157162
>salt water

No. Fresh water only. Does everyone think people who live in florida near a beach? Lol. Its and hour and a half any direction to a decent coastal fishing spot.

I did say river. Anyway. I push forward.. Because if it only works for 2 years ill get my worth out of it. And I'm not going to use it on my 35lb boat. I've opted to build a new boat to be built around the engine. Sold the 35lbr to a friend who wanted it, to fund the material cost of this new boat.. Unknown weight as of right now. But its still gonna be 8 feet long and 4 feet wide. I like this size for the small rivers I cruise on. Easy enough to turn. But tracks well going upstream. Probably going to be a flat bottom..

Its just gonna be me on the boat. Maybe another person once in awhile but mainly me.. But I am still shooting for 8 knots cruising speed.

I'm honestly trying to listen to everyone's good advice here. But I can't DO everyone's advice. So just hang in there, and don't take it personally. Ill keep everyone updated on the new build.

Op, use an old drill press gear box, the type with the lever on the side to switch while it's running

>>1152536
It isn't very much. There's 10hp pull start outboard motors that you can start yourself, and they're just as easy as the ones with a F/N/R shifter

>>1157171
I'll look into it.

>>1157183
Mine has a pull start and electric starter.. I'm planning on keeping the pull start, the motor isn't even that heavy with it on there.. I believe the motor is around 10lbs at best. I don't have a scale atm to weigh it. But when I do I will.

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I traded my bigger motor for a smaller one and 50 bucks. It runs an is in a lot better shape inside wise. I think its a 5.5hp. But also has an electric start but the wires are all chewed up.

Model number 122t05-3846-b1
If anyone wants to confirm the horse power ratings.

Damn flywheel bolt is really on there... Soaked it in PB blaster. I'm going to have to pick up a 1 inch socket tomorrow to try the rachet on it.

If anyone is curious why I'm tearing the engine down. Was to inspect everything and clean everything off. And I have to add the oil flicker into the engine to be able to run it horizontal anyway.. But the piston and valves and all that look really good. Its just getting this nut off and everything is ready for cleaning.

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Working on my bow feather today.. Heres a preview. Waiting for glue to dry as I type this. Is there anyone following this? If not ill stop updating.

>>1159353
I am, keep updating OP

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>>1159413
Thanks pham. Bonus photo for you. All glued up and ready for a light sanding then a little bit of shellac maybe.. I think I'm gonna do a few coats of shellac then spar urethane.

>>1152531
>Thats how a mower deck works.
And snow blowers. You could find one with bad engines pretty cheap and use the parts.

>>1158415
If that's a 2stroke you are looking at a bottom end rebuild

>>1157026

>27ft
>8hp
>8 knots

What kind of craft?

>>1159962

>valves
>2 stroke

2 strokes are generally "valveless"

Just uses reeds to keep the air flowing the right direction.