Timleech

I have, that particular one worked pretty well but it was too lightly built for canal use & soon got bent & battered. I may even still have it somewhere. The theoretical disadvantage of having an even number of blades is that two are masked by the stern post at the same time, so there is more likelihood of vibrations from that source. I don't suppose it's anything you would notice at normal canal speeds, but maybe if stonking along a river at speed, and particularly if your boat has a wide sternpost. I wonder if there is a fundamental difference in effectiveness between a 3-bladed prop witha large blade area, and a 4-bladed one with normal bats? Tim

I would usually fit 4 x 1.5 Kg to a 30' boat, and either 4 x 3.5 or 2 x 2.8 and 2 x 3.5 to a 50 footer (depending on what it looks as though it 'needs', a fairly subjective measurement ) Tim

I honestly don't agree there, John. It's not over-engineered for the job it has to do, in the environment in which it does it. That's not really relevant, it's a totally different situation, plus those gearbox shafts will be special steels. A boat propellor shaft has long unsupported lengths, is often made from the cheapest stainless that money can buy (though it shouldn't be ) and has to be able to cope with all sorts of abuse which the wagon engine shaft would never see or cope with. Tim

I'd like to (i) see evidence for that, and (ii) know what the actual hp & rpm are (iii) know how many hours they are expected to last for. The inland waterways environment is known to be much harsher on sterngear than salt water. (abrasives in the water, propellor impacts, ice etc). Ice can be a real killer on inadequate sterngear. I wouldn't want to put anything much bigger than a daisy on a 3/4" shaft on a canal boat Tim

It's not just the hp which determines what shaft size is needed, it's the torque. hp = torque x rpm, so the lower the rpm for a given hp, the higher the torque. Working boats with engines around the 20hp mark with props turning at about 6oo rpm used shafts of 1 3/4" to 2 1/4". I wouldn't like to go smaller than 2" with your proposed setup. 1 3/4" might be OK, but it's not a common size now. If your prop is matched to the engine, the torque load will be the same whatever the prop looks like. Yes, in general terms, the slower the prop the more efficient - especially for starting & stopping. Tim

Yes you can but it's not that simple. You have to do it at a particular proportion of full diameter, for instance. Can't remember the details. Tim

Yes. An air chisel is even better. Tim

Happens all the time with me, but then I don't sell boats Tim

I don't know the size offhand, but be aware that propellors supplied by Listers generally had a slightly smaller shaft taper, so one for a 1.5" shaft might only be 1 3/8" or so at the large end. Tim

I can honestly say that I have never done that Tim

I think they (understandably) get a bit fed up with that last bit.Wouldn't you?? Tim You don't really need 3" clearance though it's good to have. 2" is a realistic minimum where draught is limited.You can fiddle diameter & pitch a little bit, but it's not the proper answer.Better is to have the right pitch but larger blades, effectively 'folded' around the boss so they have more or less the same effect at a reduced diameter. Crowthers are the people to go to on that one, it's a problem they've dealt with quite a bit. The results won't be cheap, though, you'll be paying the same price roughly as for one of their full diameter props. Tim

No there isn't a simple answer. What you describe is quite common in a boat of that age. Either try to put it out of your mind and put your trust in the survey report, or resign yourself to hours and hours of stripping out, derusting, painting, more painting, refitting etc. The second option should extend the life of the boat, but it may be debatable whether the amount of work is fully reflected in the 'value' of the extended life. Bear in mind that rust scale is usually about 8 times the volume of the steel it came from, so 1mm of lost steel would produce 8mm thick scale. The one 'simple' thing you can do is to make sure the bilge area is kept dry and well ventilated. Tim

There certainly was a marine version of the 4.107 produced (by Parsons), I believe 4.108 also. One reason for the 'not for marine' comment may be that this range did dirty the oil very quickly, and that would have been worse in a marine duty. The marine version probably had a bigger sump which would help. Tim

No, the 4.107 was a wet linered version of the 108, usually supplied for marine applications etc. Tim AFAIR the Saab engine was made by Sachs. Tim

Mine was actually a 96 (saloon), misremembered. It had a twin-choke Weber carb, which made it reasonably lively compared to the standard offering. I remember driving from Lochgilphead to Tarbert (Loch Fyne) which is a fairly 'long & winding road', in a bit of a hurry. Halfway there I realised the plain saloon car behind me had two blokes in uniform in the front. Decided I'd best be careful, so stuck religiously to speed limits & didn't do anything silly but kept up the pace. When I pulled up in Tarbert, two coppers got out of the other car & came up to me with broad grins on their faces They complimented me on my driving, apart from suggesting I shouldn't hurry so much, & asked whether it was the standard engine as they had had great trouble keeping up with me Tim

No, it wasn't the same engine but quite similar in a number of ways IIRC Tim

I drove quite a few miles in Perkins engined transits, they were slow but sure. With the York the chance of reaching your destination was much reduced! They were an early application of toothed cambelts to diesels, my employer had one which went through IIRC 4 cambelts within 12 months from new. He'd tried to get hold of one of the last Perkins-engined Transits because he didn't trust these new fangled elastic band thingies. He was proved absolutely right Ford in Germany did a very similar V4, I had one in a Saab 95, it was a good motor. Tim

Gutless yes, but reliable unlike the awful Ford York diesel which replaced them Tim

They go back to the early sixties certainly, but how much further than that I don't know. Early diesel Transits had them, in the late sixties. Tim

Not at all, my post was just to note that fancy tiller pins aren't 'essential', nor are brass tillers Not in any way knocking those who have them. Tim

If you were able to step back a bit in time, I'm pretty sure you would find that fancy tiller pins, including the 'traditional' poker handles, were 'a bit of flash' for the working boaters and not the essential kit which they're seen as today. After all, they didn't use them to hang their lines A coach bolt would do the job just as well (without the nut). The same is certainly true of brass tiller bars, I remember them as being the exception rather than the rule in the last days of Narrow Boat carrying, certainly in the NW. Steel tube, with some multicoloured stripes if you were lucky/motivated to do it, was the norm. Tim

Yes it does mean you're not able to use the full 42hp, but don't let that worry you. If the prop is a bigger diameter than that recommended for 42hp, it will be to your advantage for starting, stopping, manoevring etc., also you may well find that general cruising is done at a more comfortable/relaxing rpm than with the smaller prop. If your test was done in shallow water, perhaps tied to the bank, you'll probably find max rpm will run a little higher with the boat moving freely in deep water such as a river. 32hp should be more than enough for a 57' nb in the real world anyway Some engine marinisers are wise to the nb situation and recommend a slightly oversize propellor. If in doubt, compare notes with other owners of similar hulls with the same engine & see what they have & how well it works. The main thing is, if it does the job for you don't lose any sleep over it. Tim

Zirconium is, I believe, better because it constantly breaks down to leave a sharp edge on the grit, whereas the ordinary brown discs just wear to a 'blunt' state. Or something. Tim

It looks as though we're talking about opposite ends of the boat Not obvious with the default typeface, but I wrote s t e m, you wrote s t e r n, I was thinking of s t e m fenders catching on cills or gate beams on the way up. There are, or used to be, one or two snags for the unwary on, for instance, the Wardle cut, where there was a length of railway iron across the face of the cill, just right for a fender to catch on when going uphill. I agree s t e r n fenders/tipcats should only be hung from above. Probably best for s t e m fenders, too! Tim

A stem fender should really be hung via weak links, traditionally a couple of strands of cotton rope, so that if it does catch on the way up the link will break and no serious damage done. This is even more important with a wooden boat Tim