Laurie NB Mary M

The 300 to re pitch is from crowthers, who made the prop. And judging by the difference in quality I've had from them and others, if like them to carry out the work.

My ruston is governed to 18.5hp @1500 rpm, shaft it 1.5" I think I'm going to chance it and try it without alteration first. You say tick My ruston is governed to 18.5hp @1500 rpm, shaft it 1.5" I think I'm going to chance it and try it without alteration first. You say tickover has increased Liam. Do you find there is any more strain on the engine? This ruston is quite similar to the ha2. Also, what was the reason for the shaft change?

Try it and see costs a day in the drydock, which is again a unnecessary expense if it means I have to do it twice and get the prop altered. But that may end up what happens. Prop altered is about £300 drydock is about £150 a day.

Thanks for the input. I've run largely over proped engines before, and your right they do stall when pulling away unless you apply higher revs. A smaller gearbox isn't an option. It's probably going to result in me sending this old one off to get altered, although some people I've spoken too said it should be ok, but I'm skeptical.

I have just built up a new engine for my boat, a ruston 2ywa with prm 402 box 2:1 reduction (which I'm aware is excessive, it just came at the right price) my question is; my current prop matched to the old engine is massively too small (16x10) however I have a old prop made by crowther which came off from another previous set up, that prop is 21x20. I have used the standard vic prop calculator which is suggesting something around 19x(can't remover pitch maybe something around 11) anyway, I called crowther about this issue, they said they could adjust my 21x20 to suit. And also asked if I had enough space to swing a 22, which I do, as that would be the ideal. Now the problem is obviously they don't let on the pitch they recommend. And I'm wondering if the pitch I have is usable with out shelling out on getting it adjusted. I know of that other downloadable prop calc program which I can't remember the name of, but it only works on PC, and I don't have that. Any input much appreciated, Laurie.

I would get an outboard and convert it to run on LPG, easy enough to do I would imagine. The kits for genies are about £100? Then you can just get the canisters from any Maria and try can swap em out for you- no heavy lifting. Very economic on running ans service intervals are not so frequent as its a lot cleaner.

but ont the problem be having to disconect the gearbox from the engine to get new belts on for the alternator every time one goes?

true about problems blocking air the other end. i was going to make a mount to fix onto the beds instead of making a bell housing. therefore not obstructing the air intake and covering in a grate for safety. but maybe attaching the same end as you might be best. i already have an alternator pulley there so could use the measurements from that to make up a plate to marry a drive plate up to. and could also have a bellhousing then which would be much neater. if your using that to run alternators too how are you going to change belts when they need replacing if its got the gearbox on the end of it? wouldnt you be better off attaching a pully on the air intake end?

ok thanks Tim. i do have a hurth hbw125 that could be used. was reccomeded a 150/260 but think a mechanical may prove to make a easier instulation for now. then maybe refit/rethink at a later date.

my plan was to go for a prm 150 and fit a jabsco waterpump on the engine, cool the oil via a bowman using the skin tank i have. but the car radiator oil cooler that you suggested sounds much better. i was hoping to mount the gearbox flywheel end as it was looking easier to do it that end. but maybe ill get a plate to fit on keyway the other end and bellhousing made up too as this would had been more of an issue the other end with the cooling etc. was it much work to make up what youve put on the end of yours for coupping? does anyone know then if a delta 20 (which i can get at a good price) or a 150 can in anyway take oposite input? cause the prop i have at the moment wont match so i will be getting a new one made anyway so not fussed about direction of output.

is it possable to run them with no alterations for either rotation as the reduction is the same in both directions? i assumed this was the case as they are comonly used on twin screw tugs etc? anyone got any thoughts on matching up a prm delta20 with my 2ywa?

variable speed. Yeah, mine is reverse rotation too, im unsure as to what to do. i could get a small mechanical gearbox and fit it to the non flywheel end which would involve more work i guess with making up a cupping system, but means i wouldn't have to worry about cooling. or i could get something hydraulic so it wouldn't mind running in either direction, i will be able to hook it up on the flywheel end, but will have to install a cooling system. hmm. how are you linking yours up to the box?

So ive just got hold of a 2 cylinder ruston hornsby 2YWA and will be sorting it all out over winter with the intention of swapping it in my boat next summer. It hasnt got a gear box or bell housing etc on it at the moment and im in the process of sorting all that out. But I'm wondering what gear box people would recommend. ive been looking at the PRM 160s and 260s but only thing is with my engine being air cooled. i dont then want to have to put in a water cooling system only for the gearbox. Any suggestions?