2 lifans in a modified kayak

Last year I built a 16ft kayak, 6mm ply went over the top with fibre tape to make sure it was nicely reinfroced for this years mod.

This years mod involve removing 4ft off the back and making it flat then putting 2 outriggers on with two engines in. (Hopefully image attached okay, engines wont be where they are in the diagram)

At a bargain price I picked up 2 Lifan 200cc 6.5hp (generator style) engines for £100 for both. (New)

I have seen many posts about a similar set-up such as http://http://www.boatdesign.net/forums/diy-marinizing/thai-longtail-mudmotor-6hp-lifan-honda-26281.html from pistnbroke.

The issue Im having is getting a clutch set up as the shaft is 20mm then to a taper, I have heard about machining it to be the right size but the bit Im confused about is the keyway, should the keyway be cut into the shaft or left pertruding, also how does the cllutch then fit securely to the shaft? Is it a grub screw?

I have tried to contact sellers of clutches in the UK for Go Kart but most are pretty unhelpful even about how the clutches connect to the shaft.

So the questions are.

1. Am i best to get a sleeve or machine it?
2. Keyway recessed or pertruding?
3. How does the clutch connect?

Ohh yeah, hi from a new member.

Rob

 

hi ..I turned out the centre of a 19mm clutch for a go kart to 20 mm but it is a very tight fit on the shaft ..dont think I could get it off without destruction...will try to take picture if you need one ....( for photos go advanced/browse / open /load ...done)


the keyway is the slot in the shaft and the key or woodruff key is the bit that slots into it ....

 

Why not two joined kayaks and one lifan. Lots of room to play on the trampoline too.

Dino

 

you will find one lifan quite fast enough...about 15 mph ..where can you go fast in the uK ...nowhere .....gear one down about 2 -3 :1 so you can fit a right hand prop...two will be difficult to control throttle balance wise ..increase noise and fuel comsumption and will not give you twice the speed ......why cut the back off ??? you dont need to do that if you use a long tail or if you must have two engines .. two props one each side ...remember the clutch will mean your min revs is about 2400 to keep the clutch engaged ...you may need to adjust spings to allow you to start it but then it engages almost immediatley

 

Thanks for getting back to me if been away a while, so ive managed to get a clutch ,cut a keyway in, tap it on the extra bit. Damn tapered shaft.

Hopefully I got a picture attached okay (this is a few weeks old).

At the moment I am in the middle of putting the drive system in. As you can see the engines fit in the outriggers,and the prop now comes out of the bottom.

This so far has been done by cutting a slot in the bottom of the outrigger for the chain to go through then making a box section for it under the hull. (sealing is what im now working on)


The reason for my ideas was to work with what I already had (kayak) but to modify it for comfort, style and as a challenge.

Not sure if i mentioned before this is a friendly challenge amongst a few friends. So far their is a 14ft speed boat with a 50hp bike engine in, jetski powered 10ft boat, similar set-up catamaran to mine (two kayaks and a roof box).


Thanks for your replies

Rob

 

if your prop shaft goes down a tube then a double lip oil seal on the prop end will keep the water out ....prop looks too big to me ....all my drawings are on this site if you look . The design in the photo could equally well have been inboard with the prop shaft tube fibreglassed into the bottom of the hull ...I think you would be very silly to take the chain below the hull when you can just put a propshaft straight out he back or through the bottom of he hull ...

 

I like what you have done and agree, this would be so much better than what I have produced. I have no way or experience in welding so it is all bolted together. I will sort out closer picture.

The prop is for a 6.5hp outboard, the system appears to work above water succesfully, athough I do need to shorten the chain so the the engine is in the outrigger.

I just have some taping to do and repeat it on the second outrigger.

 

you dont need to weld for my design ..you can use U bolts to fasten the drive tube under the engine mount plate and if you use push in plane bronze bearings you dont need a lathe

 

Just a quick comment
You thought about how you're going to seal the shaft to the hull ?

 

did this project ever get finished?

 

Ahh so we started to have a boat race, on test day mine started taking on water from the taped seams, the good thing was that on dry land the prop span well, the engines were great and when dropped in the water the boat (contraption) apart from taking on water sat where I wanted it to.

Everyone elses boat went down quickly aswell, except the jet ski engine boat who had electrical failure.

It has been stored for now but we are redoing it for september so in a few weeks I will be restarting it. It needs another brain wave of thought some more tape but it may end up being just the one engine after all, maybe strapped to the centre as a long tail. Ill add some more photos soon.

 

I looked at using a double lip rotary oil seal, not sure if it will hold, im currently back on the build on the weekends anyway.

 

i dont understand the comment about the shaft ...shurely the drive shaft will pass down a tube which is glassed into the hull and have a seal at either top or bottom ???

 

Hi all,
Sorry, I know this is an OLD thread but.....
I'm considering something like this as an onboard on a custom built, 1 man mini boat.
15mph is an incredible speed for such a cheap motor and should even allow my planned design to plane!

The main thing I am concerned about is noise level.

I used to be a go kart mechanic and so am across the mechanical and clutch side of the project but have never heard one of these engines in stock form. All the kart engines are quite loud but their exhausts are HEAVILY modified (if existent at all.....)