Horizon 26 / 1GM10 Power issues...!

Belated update:
Air intake and filter are fine, and the exhaust elbow has minimal carbon.
The engine revs happily to 3800rpm in neutral with nice clear exhaust.
In gear (stationary in marina) she will only rev to 2100 in gear, with horrid black smoke out the back!
What rpm should she rev to in gear (assuming not over-propped, small 2 blade)?
Prop shaft turns easily by hand in neutral.
Would a rope around the prop give this sort of picture? Would it feel solid turning by hand if this was the case?
Could it be a gear box problem? (gear box oil is nice and clear looking)
Any other thoughts?
Thanks again for any advice.
Jonathan
 
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tied up along side you will not get full revs & will get black smoke
under way you should get hull spd @ max revs, you might get some black smoke

Mwinda said:
Belated update:
Air intake and filter are fine, and the exhaust elbow has minimal carbon.
The engine revs happily to 3800rpm in neutral with nice clear exhaust.
In gear (stationary in marina) she will only rev to 2100 in gear, with horrid black smoke out the back!
What rpm should she rev to in gear (assuming not over-propped, small 2 blade)?
Prop shaft turns easily by hand in neutral.
Would a rope around the prop give this sort of picture? Would it feel solid turning by hand if this was the case?
Could it be a gear box problem? (gear box oil is nice and clear looking)
Any other thoughts?
Thanks again for any advice.
Jonathan
Click to expand...
 
sailorman said:
tied up along side you will not get full revs & will get black smoke
under way you should get hull spd @ max revs, you might get some black smoke
Click to expand...
Agree with this. Certainly, on my Hunter 245, if boat is moored alongside pontoon, running the engine as fast as possible gives lots of black smoke (haven't checked revs) but there's not a lot of smoke on full chat when the boat is free to move.
It's possible that if you run the engine with the boat not tethered, you might not get black smoke (or, at least, not as much).

I'm still baffled by all this. Even at 2100 rpm you should get more than a couple of knots.

The photo showed what looked like the "usual" prop but I can't be sure. The diameter and pitch should be marked on the propeller boss, probably as 14" x 10" or thereabouts, you can easily measure diameter in any case.

Have you looked at max speed recently? has it improved at all, or is it still down to a couple of knots? how recent is that photo? you might be coming up to scrub time by now ...
 
The factory fitted prop on my ex Hunter horizon 27 looked like the one in your picture, 2 blade and had what looked like 14x8.5" stamped on the boss and had a 1GM10 engine. At full rev's in gear at sea I could get between 2800rpm to 3000rpm with no black smoke top speed under engine in normal sea conditions was around 5.5 and 6kn over the ground, there was a air vent in the transom leading to the cockpit locker and another from the cockpit locker into the engine compartment and another one above the top step in the companion way.
Most likely over propped but check the shaft is free to turn easily,foam in air cleaner has not come unstuck and blocked air inlet also I found that the exhaust outlet port in the head was prone to getting partially blocked with carbon and just another thought The exhaust system,water-lock,pipe is clear isn't it..
 
Mwinda said:
Belated update:
Air intake and filter are fine, and the exhaust elbow has minimal carbon.
The engine revs happily to 3800rpm in neutral with nice clear exhaust.
In gear (stationary in marina) she will only rev to 2100 in gear, with horrid black smoke out the back!
What rpm should she rev to in gear (assuming not over-propped, small 2 blade)?
Prop shaft turns easily by hand in neutral.
Would a rope around the prop give this sort of picture? Would it feel solid turning by hand if this was the case?
Could it be a gear box problem? (gear box oil is nice and clear looking)
Any other thoughts?
Thanks again for any advice.
Jonathan
Click to expand...

Still nothing about the prop. Your problem is almost certainly a fouled prop, or possibly, but unlikely an oversize prop. If the engine starts and runs well without load then unlikely to be an engine related problem. You should be able to get around 2800 in gear moored up before it starts to labour and at least 3200 when underway.
 
my 4 cylinder engine rated @ 3000 RPM will pull no more than 2100 RPM along side.
i cant see this 1GM getting to 2800


Tranona said:
Still nothing about the prop. Your problem is almost certainly a fouled prop, or possibly, but unlikely an oversize prop. If the engine starts and runs well without load then unlikely to be an engine related problem. You should be able to get around 2800 in gear moored up before it starts to labour and at least 3200 when underway.
Click to expand...
 
When I take a ruler to the image of your boat, the length across the tips of the prop is almost 2X the length across the stern ladder. assuming the stern ladder is about 12 inches, that puts the prop nearer 24 inches. Bearing in mind that the prop is also further away, it can't be much smaller. You need to measure the diameter of the prop from blade tip to blade tip next time she is lifted.

The 1GM10 is supplied with three gearbox ratios 2.21:1, 2.61:1 and 3.22:1. The ratio fitted is stamped on a plate mounted on the upper aft face of the flywheel bellhousing.

My boat is a 24ft Eygthene fitted with a 1GM10. I was advised that ideally I should order an engine with a 1:3.22 gearbox ratio and fit a 16 x 10, 2 bladed folding prop. In fact there is not enough tip clearance for such a big prop on the Eygthene 24 (needs 10%). I was then advised to order a 12 x 8, 2 bladed folding prop with a 1:2.21 gearbox, which I fitted. The boat does 5.5 knots with 2800 revs and no black smoke and the engine has been used over four seasons with about 100 hours per season. It can comfortably rev up to 3500 in gear with a bit of an increase in speed through the water.

With the 1GM10, your boat ought to be doing about the same. You need to check the gearbox ratio and measure the size of the prop. I am pretty sure you will find there is nothing wrong with the engine, but that it has the wrong prop.
 
My engine swings an 18" prop
a 24" prop would stall a 1GM, you would need @ least a 38m/m shaft for a 24" prop i would think he has a 20m/m shaft fitted



QUOTE=Eygthene;4023182]When I take a ruler to the image of your boat, the length across the tips of the prop is almost 2X the length across the stern ladder. assuming the stern ladder is about 12 inches, that puts the prop nearer 24 inches. Bearing in mind that the prop is also further away, it can't be much smaller. You need to measure the diameter of the prop from blade tip to blade tip next time she is lifted.



The 1GM10 is supplied with three gearbox ratios 2.21:1, 2.61:1 and 3.22:1. The ratio fitted is stamped on a plate mounted on the upper aft face of the flywheel bellhousing.

My boat is a 24ft Eygthene fitted with a 1GM10. I was advised that ideally I should order an engine with a 1:3.22 gearbox ratio and fit a 16 x 10, 2 bladed folding prop. In fact there is not enough tip clearance for such a big prop on the Eygthene 24 (needs 10%). I was then advised to order a 12 x 8, 2 bladed folding prop with a 1:2.21 gearbox, which I fitted. The boat does 5.5 knots with 2800 revs and no black smoke and the engine has been used over four seasons with about 100 hours per season. It can comfortably rev up to 3500 in gear with a bit of an increase in speed through the water.

With the 1GM10, your boat ought to be doing about the same. You need to check the gearbox ratio and measure the size of the prop. I am pretty sure you will find there is nothing wrong with the engine, but that it has the wrong prop.[/QUOTE]
 
Thanks all, appreciated.
I doubt the prime problem is too big a prop, I suspect the picture gives the wrong impression as it doesn't look big, but I can't check right now!
(I also say that as its a relatively recent change - not sure performance under engine was ever stellar, but its dismal now!!)
I'll dry her out next and have a look.
So if there nothing else in the transmission that could be causing the problem, given that there are no horrid noises, and the gearbox oil is clean?
I'm thinking of transmission problems/faults rather than in-correct ratios/installation.
Cheers!
s/y Mwinda
 
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sailorman said:
my 4 cylinder engine rated @ 3000 RPM will pull no more than 2100 RPM along side.
i cant see this 1GM getting to 2800
Click to expand...

What your engine does or does not do is irrelevant to a 1GM which runs to 3600 rpm and according to the maker should be propped to active a minimum of 3200. Cruising revs 2800.
 
Eygthene said:
When I take a ruler to the image of your boat, the length across the tips of the prop is almost 2X the length across the stern ladder. assuming the stern ladder is about 12 inches, that puts the prop nearer 24 inches. Bearing in mind that the prop is also further away, it can't be much smaller.
Click to expand...
No offence intended but your suggestion betrays a slightly tenuous grasp of perspective. A 24" prop would fill much more of the gap between the hull and the hard it's standing on. I would have said that's a 12 or 13" prop which would be about right as others have said. My money is on a big plastic sack or some such wrapped around the prop.
 
Well drying out will be in about 3 weeks now, so hopefully all will be revealed (so hoping it is a bag round the prop!)
Micky - fascinating post , your technical skills exceed mine, offer for details appreciated if it's not a bag!
 
Have you tried looking at the prop? OK, it's a bit cold for a mask and snorkel, but a glass/perspex bottomed bucket should give you a good idea of what's going on. Might even be a good excuse to acquire a video camera that works underwater.

Even with a badly weeded hull and barnacled prop I can make 3kts in my 27 footer, the only time it was worse was when I caught a fertiliser sack.
 
My Ranger 245 did that at the end of one season (slow + lots of smoke)
I dived underneath. Lots of stringy weed on the propshaft and propeller.
Cleaned it up. Problem fixed
 
fastjedi said:
My Ranger 245 did that at the end of one season (slow + lots of smoke)
I dived underneath. Lots of stringy weed on the propshaft and propeller.
Cleaned it up. Problem fixed
Click to expand...

Similar experience with previous boat - a Hunter Horizon 272 with the 1GM (normal cruising speed 4.5-5kn). Just going into a very tight anchorage & went over a patch of floating weed. Boat slowed dramatically but cleared enough to get anchored. Cleaned it up from the dinghy with a boat hook and no more problems. I really hope your solution is as simple.
 
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