Replacement for 1GM

25931

25931

Well-Known Member
Joined
22 Aug 2008
Messages
5,382
Location
Portugal-Algarve
Visit site
We are cosidering replacing the old Yanmar and would appreciate advice. Overall dimensions have to be considered and, to a lesser extent, weight not to mention price.The Beta 14 appears to be a practical option but how about the Yanmar 14 ?
 
Have recently replaced a 1GM with a Nanni 14. Dimensions are virtually identical, although engine mounts are slightly further apart and a bit higher, solved by bonding a strip of wood on top of the existing (wooden) bearers. The only dimension that might give difficulty is at the top back where the extra cylinder means it has more bulk where the expansion tank is. In my case I had to remove a bit of a non structural bulkhead to get clearance. The exhaust is on the opposite side and is 40mm rather than 45mm. Not insurmountable if you have the space and an adaptor for the diameter change, but I understand that Beta offer a bend that takes the exhaust back to the starboard side, and presumably the correct diameter rather than their standard 50mm.

You will need to change the water inlet and strainer to a 3/4" as your current 1/2" is not big enough. The bolt spacing on the gearbox coupling is different from the Yanmar so you will need a new coupling. I used a Bullflex which was already on the Yanmar with an adaptor, but the common one to use is a Centaflex type. Check carefully on the gearbox ratio. If you currently have a 3.1:1 then you should be able to run the same prop on a 2.6. If you have a 2:1 or 2.6:1 currently you may need to change the prop.

Think you will find the Yanmar 15 is physically much bigger (and when I looked much more expensive)

Hope this helps.
 
Many thanks, Tranona. I think that Nanni & Beta are from the same Kubota base. Did you get a better price or was there another reason for your choice ?
 
You are right about the two engines being much the same apart from some minor differences. I had a 1GM10 in the old boat and then a new Beat 14 installed in the new boat.

Beta do claim to make installation easy with purpose built engine mountings. I would haver a look at both and look for any things that are better on one for the space you have. I love my Beta but with it installed in my boat, getting the heat exchanger stack off is extremely difficult because of the access. A ten minute easy job with proper access becomes a real pain.

I imagine the Nanni and the Beta both have their individual peculiarities.
 
The price will almost certainly be the same for comparable specs (alternators, sump etc where there are options). I think the marinising, particularly the heat exchanger is better on the Nanni - partly based on the regular reports here of short anode life and silted up tube stacks - but that may be because there are more Betas around. Final decision was based on colour - blue matches my boat better.
 
That's interesting, I thought the 1GM10 had been discontinued. Spares are available and personally I'd not replace the engine unless the head was gone or the main and/or big end bearings were shot. It's well within the capabilities of anyone with basic DIY skills to do a top end overhaul and my engine was as good as new after I did mine.
 
25931 said:
We like the idea of two cylinders and a bit more power - the entrance to the Ria Formosa (bar ,Faro & Olhão) can be interesting, running at six knots with big springs.
Click to expand...

You will find the 40%+ power increase with the right prop will make a big difference. Quieter and smoother across the range. Noit that the 1GM ia a bad engine - in its time it was the only good sub 10hp engine, but things move on.
 
25931 said:
We like the idea of two cylinders and a bit more power - the entrance to the Ria Formosa (bar ,Faro & Olhão) can be interesting, running at six knots with big springs.
Click to expand...

I think the 2YM15 would be an ideal replacement for the 1GM10 you can keep the same shaft and coupling as the gearbox is the same, just change your prop!
 
There is a trend these days to fit larger engines than is strictly necessary. When I replaced my old Volvo, I was encouraged by many to go for the twin. It was wholly unnecessary as my 1GM10 drives the boat at hull speed and any attempt to screw a little more speed from the boat just drives the stern lower and the exhaust slips below the waterline on certain tacks (this might not be a problem for you). In my case the situation is self limiting. The heavier engine would exacerbate the problem for no improvement in performance.

Cats are notoriously easier to drive through the water than monohulls. Any attempt to put more power into the water than needed to drive the vessel will result in wasted fuel, cavitation and so on. Running a diesel at light loads leads to the possibly engine damage as bore can get glazed causing poor piston ring sealing. My reccomendation is that you find out how much power you actualy need to drive the boat at hull speed (whatever that is, I'm no Catalac expert) By all means add a couple of BHP to account for headwinds and choppy seas if it makes you feel comfortable but I"d not reccommend doubling the power output.

If the 1GM10 is to be replaced and it drives your boat well, by all means go for the Beta 12 (a twin) but the Yanmar really would be overkill. Remember the 1GM10 is raw water cooled and the current twins are freshwater cooled so you'll need to accommodate the additional weight of the heat exchanger and "fresh" water plumbing.
 
The Beta (and Nanni) is 13.5 not 12 and is a real step up in refinement from a 1GM - not that the Yanmar is bad, but things have moved on in the last 30 years since the 1GM came out. The difference in weight is minimal, less than 20 kilos and all the other key physical dimensions are virtually the same. If you are really worried about it being overpowered (unlikely on the OPs boat) you can always save a few £s and get the 10hp version.

Given that the expected life of an engine is well over 30 years it is probably a good idea to fit a current design engine rather than one that is at the end of its design life.
 
Tranona said:
The Beta (and Nanni) is 13.5 not 12 and is a real step up in refinement from a 1GM - not that the Yanmar is bad, but things have moved on in the last 30 years since the 1GM came out. The difference in weight is minimal, less than 20 kilos and all the other key physical dimensions are virtually the same. If you are really worried about it being overpowered (unlikely on the OPs boat) you can always save a few £s and get the 10hp version.

Given that the expected life of an engine is well over 30 years it is probably a good idea to fit a current design engine rather than one that is at the end of its design life.
Click to expand...

Don't write off the 1GM as its still produced and even though its raw water cooled, its cooling system is designed to cope and will last the life of the engine. Everybody seems to quote Nanni and Beta and they both use the very respectable Kubota, however, try to get the chance to look at 2YM15 you won't be disapointed!
 
No complaints about Yanmar. Did consider a 2YM. However it is 40mm longer, 50mm wider and crucially 86mm higher than the Beta/Nanni. Plus to use my Bullflex coupling you need to add an adaptor which is 15mm extra to installed length. End result will not fit the same space a 1GM comes out of, whereas the Nanni fits perfectly - just 5mm extra length.

Appreciate not everybody has the same space constraints so, assuming the price is the same the Yanmar comes into the frame.
 
Tranona said:
No complaints about Yanmar. Did consider a 2YM. However it is 40mm longer, 50mm wider and crucially 86mm higher than the Beta/Nanni. Plus to use my Bullflex coupling you need to add an adaptor which is 15mm extra to installed length. End result will not fit the same space a 1GM comes out of, whereas the Nanni fits perfectly - just 5mm extra length.

Appreciate not everybody has the same space constraints so, assuming the price is the same the Yanmar comes into the frame.
Click to expand...

Fair enough
 
Bretonbrit

One of my Gm10s packed up as I sailed over to the uk a fortnight ago,about time I got them
refurbished,I'm in Millbrook til next spring,can anyone recommend a good yanmar engineer in the Pymouth area to do a recon,or within 100 miles or so.
 
I have a piar of 1GM10's in my Catalac 8M. I rebuilt one last year. I used my boom and topping lift to swing the engine out of the engine compartment and place it on my cockpit floor. The rebuild took 3 days for machining (bored the cylinder and ground the valves) and 1 morning for reassembly. New rings, new bearings, water pumps, fuel lines and of course all new gaskets.

The final cost was so reasonable as to be unbelievable and the engine is good for another 30 years.

I know of two Catalac 8Ms that repowered using "V-drives" to fit the 2cylinder Yanmar. Both spent a fortune and the result was the same for both owners. The boat just buried her stern almost up to the swim platform when full power was applied. Both owners then sold the boat.
 
The beta and the nanni are both good options for the catalac, and provide that extra needed push when pushing against the wind.

any larger and you do really have problems of burying the stern.

Biggest problem is the propellor as the standard 2 blade prop for the 1GM needs to be a fairly small diameter and thus it is difficult to ge tthe power into the water.
 
You must log in or register to reply here.

Other threads that may be of interest

B
How does a tacho get RPM and engine-hours data, and how to fix faulty readings?
Replies
16
Views
433
Babylon
B

Share this page

Top