Too big an engine or too small a prop?

I tried the maximum revs thing tonight...

Against a good tide and 10kn wind with no sails, I could get about 3300 revs at full throttle..

So does that mean the prop is pretty much exactly suited for the 2010 engine?

thanks for all the advice so far, when I next get her out of the water, I'll have a good look at the prop to see if I can see what sort it is?
 
What speed were you getting through the water? The revs are OK. You said it had a 20hp engine. The 2010 is an 11hp. A 20 will be either a 2002 or 2020. They are very different engines. Before messing about with it, you do need to know which engine and leg you have. If it is an old leg it could be a 110 or a later leg is a 120. They have different reduction ratios. If you have a 20hp engine you should get over 5 knots through the water at 2400 and 6.5 at 3300. If it is a 11 hp you will probably need 2800 to get 5 knots.
 
Tranona said:
What speed were you getting through the water? The revs are OK. You said it had a 20hp engine. The 2010 is an 11hp. A 20 will be either a 2002 or 2020. They are very different engines. Before messing about with it, you do need to know which engine and leg you have. If it is an old leg it could be a 110 or a later leg is a 120. They have different reduction ratios. If you have a 20hp engine you should get over 5 knots through the water at 2400 and 6.5 at 3300. If it is a 11 hp you will probably need 2800 to get 5 knots.
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That's very interesting! I'm sure he said it was a 20hp 2010! so maybe he was a little confused. I'll have a good look on the engine for all the codes and stuff to be sure..

I've no idea how fast I was going, as the only speedo on the boat is something you chuck out behind, and I think I'm too young for that sort of technology :-)
 
If it is a small 2 cylinder from around 1992 to 2005 then it is a 2010 11hp. The 20 hp 2020 is a 3 cylinder. The older 2002 18hp is also a 2 cylinder, but much bigger and more agricultural. The earlier 10hp 2001 is a single cylinder. Pity they are all painted green!

A 2010 is a good little engine, but a bit marginal for the size of boat by today's standards and you may find your speed compromised a bit by a folding 2 blade prop, particularly if it is an older design. The best performing props for power are the standard 2 blade fixed, but obviously you have extra drag under sail.
 
chrisbitz said:
That's very interesting! I'm sure he said it was a 20hp 2010! so maybe he was a little confused. I'll have a good look on the engine for all the codes and stuff to be sure..

I've no idea how fast I was going, as the only speedo on the boat is something you chuck out behind, and I think I'm too young for that sort of technology :-)
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I can't help with any of your question as I know bugger all about anything! But, as for your speed, there are a multitude of smart phone apps that can show your speed using GPS, assuming of course you have a smartphone!

Cheers,
Chris
 
I had a good look over the boat, and found the details in the service manual.

It's a MD2010 C (or s?) What does the C mean? I could only see it's larger cooling capacity?

The gear Ratio is 2-48... What ever that means! :-) I'm guessing it's different to 1:24?

The prop is a 14x8 folding.

it's done about 200 hours - what hours are significant on boats? How many hours between services/overhauls?


I really appreciate all the info from the guys that these specs mean something to!
 
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Agree. Standard setup. Prop about right. Maximum revs is 3600, but 3300 OK. Should give you just over 6 knots through the water and cruise at 5 knots at around 2300-2400. Might be a bit slow to stop in reverse depending on which type of folder you have. Whole life ahead of it, 8000 hours not unusual. My 2030 (3 cylinder version of yours) has 3500 hours on it and runs as well as it did new.
 
Can I just take this thread on a slight diversion. If you think a boat is otherwise an attractive proposition but the engine is too big (40HP on Sadler 32) is there anything you can do to make it work? (I speak without the benefit of a sea trial here) - if its a matter of a larger prop then it would presumably have to be folding/feathering to avoid too much drag
 
NigelCraig said:
Can I just take this thread on a slight diversion. If you think a boat is otherwise an attractive proposition but the engine is too big (40HP on Sadler 32) is there anything you can do to make it work? (I speak without the benefit of a sea trial here) - if its a matter of a larger prop then it would presumably have to be folding/feathering to avoid too much drag
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There will probably be a limit in diameter determined by the distance between the prop centreline and the hull. Recommended tip clearance is 15% diameter so a 15" prop requires a minimum of 8.5" from the centre of the shaft where the prop is to the hull. Given this limitation you will probably have to increase "size" by increasing pitch to put more load onto the engine for given revs so that you constrain the amount of power produced by the engine. It will run at lower revs than is ideal, but still put load on to avoid the problems of running long periods at low load. It is irrelevant whether it is a fixed or folding prop as the extra pitch does not change the amount of drag significantly. of course a folding prop will have lower drag and you can still have higher pitch blades.

presumably you are thinking of the VW engine that was fitted to some of those boats. If they were installed by somebody who knew what they were doing they would have been fitted with an appropriate reduction box and prop.
 
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