Proper Job

Dennis Did you ever find that stuff on my engine again? or will it have to wait for next years spring clean? The original tread was titled "Ailsa Craig" - engine info wanted. Cheers

Rog Sound interesting - is that Reading Maine Co or Reading Marine Services? Reading is not a million miles away from me. Bruntons recon a 4 blader is better at reducing cavitation when going from ahead to astern. How does this comapare with yours? What made you change from 3 to 4 in the first place?

Although the manufacturers of these mounts claim that they absorb a lot of energy, I have never been convinced that they do, I have used them in other industries and have always suspected they simply pass energy on and change it's frequency like a spring. A good point. I seem to remember something about 'energy cannot be created of destroyed - its form can only be changed'. A modern engine mount can only change the frequency to that of a less annoying/detrimental one? Before we get to carried away on the prop shaft diameter - I think I'll stick with the 2". I have previously destroyed a prm gearbox by hitting a tree stump (1500 rpm to 0 in 5 nano seconds) and ridden over a submerged car whilst using the prop to open up the roof! The 'ting - ting - ting' sound it made was most disconcerting!. I've not heard of anyone breaking a propshaft, but I have heard of them being bent.

Dear All Some interesting feedback fro Bruntons propellers. They don't make anything under 30" diameter but still ran the calcs based on all of the info I gave them. ie boat design, displacement etc etc. I did say that I would like to try to restrict the diameter to around 24". There response is below "I have had a quick look at the sizing, and got a similar result to Ailsa Craig at 28", ie 28 x 21, 3 blades. However the optimum diameter is around 30". A 24" propeller will not be particularly efficient becuase of the diameter restriction (a 24" would require around 27-28" of pitch). If you are restricting to 24" I think a four blader would be best, as the boat is so heavy it would reduce cavitation when manoeuvring etc. A typical blade area ratio for a standard four blader is approximately 0.70 (70%)." Does anyone run with a 4 blader?

For what its worth: We've been talking to a lot of builder in the quest to select a builder of our new boat. Norton Canes Boatbuilders have a standard build/painting process. The hulls etc are built, left outside for a few months to rust, before being bought back in, shot blasted and then painted. In Grahams words - it allows the steel to rest after the bending, heating & welding and then helps get rid of the millscale before final cleaning up and painting. Another reason why his boat are a little bit more expensive than most, but its this understanding and attention to detail that costs but reaps dividends in the future?

Thanks to all of those who have replied. I will contact Crowthers in due course, I just wanted to get my head around it before I did. A couple more questions around the subject though: Someone (outside the forum) told me that the key thing was to not exceed 70% of the prop blade area v's 'disc' area of the prop diameter. The lower the percentage the more efficient the prop. Thus Ailsa Craig states 28" with a blade area of 270 sq in. 28" diameter gives disc area of 616 sq in = 44% Assuming the blade area remains constant at 270 sq in 26" dia = 531 sq in = 51% 24" dia = 452 sq in = 60% 22" dia = 380 sq in = 70% etc, etc Does that mean that I could run a 22" prop if the blade area is still at 270 sq in. Or is the above total b#####ks? Another question: 2" propshafts and stern gear is relitively quite expensive. 2" for 40hp seems very high. By reducing the diameter of the prop will the imposed torque on the shaft exerted by the prop reduce (as torque is force x radius) and will that mean that a lesser diameter (cheaper) shaft/gear gear will be required? I'm not sure that removing the 2:1 reduction gear will be possible without chaging the whole gear box. Besides, I thought that the slower a prop rotated, the more efficient it was? Any thought you technical bod's?

I know it comes up in the forum quite often, but I've looked through many threads and can quite find what I'm looking for. Ailsa Craig specified for their RFR4 engines (40hp @ 1200rpm - 2:1 reduction box) the following prop stern gear requirements: 28 x 21 prop, 3 bladed, 270 sq in blade area. 2" tail shaft with 2. 7/8" stern tube. Allowing 3" top & bottom for clearance, that gives a starting draft of nearly 3 feet. The prop only turns at 600 rpm flat out and will spend most of its time running a lot slower. Is it possible/advisable to reduce the diameter and increase the pitch. Thereby reducing the draft a bit. It will be fitted in a yet to be constructed tug hull (62' - maybe a Jonathan Wilson). I know prop sizing is a mine field, but its expensive to get it wrong!

Mike I 'saw' this engine. It came up as a 'google' when I was looking for Ailsa Craig info. The RL2 appears on the face of it to be the same/similar to the RF series of engines - output of 20hp @ 1200rpm etc, etc. I sent a letter to Dr Robert Kisch. He replied very quickly and gave me a lot of info about some of the more specific questions I asked about the RFR4's. From the advice given I am almost 100% sure that both engines can be restored. I have also been touch with Kevin Whittle. He is going to put me in touch with an owner of an RFR3. Thanks to all

Thanks for the info gents. I've found an address for Dr Kisch and have written to him. I should have been a bit more specific with the question. The main reason for asking is because I have just obtained a pair of Ailsa Craig RFR4's. The engines are about 95% complete and both should be restorable (that's the optimist in me as I havn't even tried to turn them over yet, let alone remove anything). They appear to have a very 'interesting' gear change mechanism. Do they have a seperate clutch lever to the gear selector? Does anyone know of any current users of RF/RFR engines? I'd love to be able to see one installed. Any further help would be appreciated

Who is a guru for Ailsa Craig engines? Info on the www is pretty rare. Any contacts, links etc would be very useful.

We had a 1.5 Thorneycroft based on the BMC in a 50 footer. It was used on the Thames for most of its life and would punch up against fast running streams with no bother. We also 'over-ran' a trip from Limehouse to Teddington and had to overcome the out going tide. The old girl was running virtually flat out for well over an hour and came up with the goods. Good reliable work horses! Steve

I understand what your saying about parts. I've found one web site that show three different sets of mains (from three different manufacturer's). So they are far from standard. My understanding was that the Kingfisher was a one off design and rev'ed fairly well. The Indian CS/Petters are based on a long standing british design that should (hopefully) have longevity built in to it. The other thing I wasn't sure of was speed control and governor linkaging. As the engine is designed to run at a fixed speed and variable load, speed control on the CS is via a set of centifugal wieghts. I've heard of marinised Lister CE's but never CS's - just wondered if anyone had tried it?

With vintage engines becoming scarce. Has anyone ever considered the Indian 'Listeroids'? Basically a CS Lister, but shouldn't be to difficult to marinise. 24 hp@1000rpm. 2 cylinder thumper. Check out: www.poweranand.com £1,645.00 for the basic motor all duty paid imported to the UK via their agent. A water circ pump is an extra £50. There is even an electric start option. Gear box, a bit of engineering nounce and away you go. Plenty of crankshaft to drive alternators etc at the other end. Theres a lot of info out there in www land about off grid power generation from these beasties - running on waste veggie oil too. Or the Petter twin - 25hp @ 1500 rpm. What do you think?

Interesting comments about the wether to building the boat around the engine or the engine in after. Its a bit of a dilema. I think a lot of it will depend on build timescales. The engine is basically sound but I was going to give it a good going over before installation. She needs a full repaint and a lot of cosmetic work as a minimum. Any work that needs doing is easier done in my warm garage with plenty of light and room. 'Her in doors' wants the NB build to start as soon as a builder (once selected) can. The engine might not be ready to supply. K3 install instructions advise a hole minimum 6' x 2' 9" to fit engine through. Plus she weighs 3000lbs. Thats a big hole to subsequently span with a plate. The worry in supplying the engine prior to building is what happens during the construction phase. Theres a lot of sparks, metal dust from grinders etc, etc. I would hate to think of her first breath as being one full of grinding dust! Dilema's, Dilema's

Fair comment - indeed they have, but I'd rather be doing a steady 600 revs and getting over an hour to the gallon. Just a matter of choice

R W Davis is on the short list - a bit heavy on the rivits? - (just an initial opinion). As is Johnathon Wilson and Norton Canes Boatbuilders (mind you Grahams a Gardner man and he's trying to convince that the K3 is to big and I need a Gardner!) I'm not so sure about the 30" prop Daniel. I don't want to use her for water skiing. Put her in reverse and I'll empty the canal! I was thinking more on the lines of 26 x 26 Steve Who else out there has a K3 in a boat. I need some help with engine room design and it would be a shame to re-invent the wheel. Size/plans/speed wheel/gearchange setup/shaft and prop arrangements? - anything would be useful Steve Interesting you should say about the river. Most of our weekend cruising is in the Thames. It would be most upsetting for the airfix kits to be overtaken by a NB at 600 rpm! Plenty of depth to give her some work! Steve

It can be done without sinking the boat. I've done it. But its a real 'challenge'. Preparation is everything. You've got to remove the rudder - how easy this is will depend on how its fitted. Make a plate up that fixes over the stern gland packer and uses the same hole centres and the stern packer studs. A piece of soft'ish rubber of the same shape. Tie rope around the prop blades and up on the the rear deck (stops the embarisment having to go fishing for the prop/shaft assembly) and a rope through the weed hatch (this stops the shaft & prop slipping out in an uncontroller way. Remove coupling and any key from the shaft inside. With a person on the back deck holding the rope, push the shaft back in to the stern gland. Remove the sterngland 'packer'. Be ready with your made up plate. This is where you can get wet. DO NOT PUSH THE SHAFT TO FAR DOWN THE TUBE AS LOADS OF WATER WILL COME IN! Make sure the man with the rope don't get carried away and pull it right out Once the shaft is back in the tube put your made up plate and rubber joint over the hole and tighten up on the sterngland packer studs. You should be water tight without getting to wet. With someone in the weedhatch guiding and someone on the rope the shaft can then be withdrawn. Putting it back is the reverse. You need a lot of patience as it can take ages to feed the shaft back in to the tube. Hands get very, very cold. Good luck If in doubt. Dry dock/crane/slip!

OK all. I've lost the plot and gone and found a Kelvin K3. All I've got to do now is find someone to build the boat around it. A serious beast - I thought the JP3 was a lump but this is exceptional. 3 cyl, 12 litre, 66hp. 6 feet long, 5 feet high. Flat out 750 rpm. Ticks over at 80 - 100 rpm. A sound to die for! Don't think I'll need to much ballast as it weighs 1.5 tonnes. Do I need a white coat with the wrap around sleeves?

I've done the middle level twice on trips from Oxford to Cambridge. Endless miles of bordom. Make sure you have a trad' style stern. The only way you can see anything over the high banks is to stand on the roof and steer with your foot! Don't worry though, you don't need to steer much as they go in endless staight lines. Beware of slipping in to a coma. Beware of the rain. It only seems to be able to come down in a horizonal direction!