Jump to content

Beneteau First 27: Question on the compatability of Yanmar 1GM10 with Gori Propeller


Recommended Posts

 Dear Braniac anarchists.. Some of you may have been following my frustrations with the water leak on my First 27. (7.99M) and gave me good advice.   The leak is  not fixed yet... But the temporary bodge had held for the season so far. And its proved to be a very good sailing boat for amateurs like me.  Now I am seeking advice from the  SA sages on my engine propeller/combo. Boat declared weight is 1700KG so I suppose about 1900KG with fuel water and my junk.  She has a  10 HP 1GM10 single cylinder with a 1:2.21 ratio gearbox and a 13x 9 Gori folding propeller. The engine doesn't  cope  at all well with the revs dying at the slightest provocation of wind  or current. Making way at 1.5 knots  with clouds of smoke does not instil confidence. 

Beneteau/Seascape have now switched to a 15hp engine I believe but I am quite happy with my little thumper if we can get it to rev. I like having an inboard but still like to keep the weight to a minimum.

Any suggestions please on what I should do? Should this combo work effectively? Do I need a smaller propeller or is there potentially something else wrong? Could  possible misalignment of engine and propshaft eat a lot of power?  All comments much appreciated

Link to post
Share on other sites

 Can you get to 3600 RPM  in flat water, no wind or waves? If not, you are overpropped. The engine is only 9 HP not 10. After going through 2 x right angle bevel gears you might be putting only 8 HP to the prop...

I would talk to Gori, but sure sounds like too much prop. For 9 HP  I would expect 12 x 9 or so. 

 

Link to post
Share on other sites

Thanks Zonker. I dont know what revs I can get as there is no Rev counter but it's certainly much less than the free revving engine out of gear in calm conditions 

Link to post
Share on other sites

A boat that light should do fine with that engine - it must be the prop.

I had a YSM 8 in my 4300 Lb QT and it had lots of surplus power with a Martec - don't remember the size.

Link to post
Share on other sites

 clean bottom and prop? how many hours on the engine? is this the stock prop? how fast on calm water will it go?  sounds more like a engine problem. time for new injector?  get a hand held tach  and check engine and propshaft RPM while underway only way to know for sure what the problem is.

Link to post
Share on other sites

I have the same engine and (I think) the same gearbox in my Alerion 28 and run a 12x12 folding prop.  It will just make full revs under good conditions, so I guess it's about right.  No speed demon, that's for sure!

Link to post
Share on other sites

It's a new engine with about 30 hours on it. Unfortunately the Yanmar A instruments were fitted which do not have a rev counter  (I requested the B option but was informed not possible ) I have tried to source a different external rev counter but that has proved difficult here . But no way does it rev to 3600 RPM.   My impression is that it is maybe overpropped but Seascape insist that is not possible as their first factory boat is apparently fine. But I don't know what gearbox ratio they have on that boat.   

Link to post
Share on other sites

I’m sure glad that the boat sails nicely.  At this point, may I suggest that you rip out the engine and shaft, pound a wooden plug into the hole with some 5200 on it, and contract with the local boat boys to tow you to and from the starts?  Bene should be cringing with embarrassment.  And yeah, I love it when something is clearly wrong with new machinery and the factory says “Oh, what you are seeing can’t be happening.”  Wankers.

Link to post
Share on other sites
14 minutes ago, The great unwashed said:

I’m sure glad that the boat sails nicely.  At this point, may I suggest that you rip out the engine and shaft, pound a wooden plug into the hole with some 5200 on it, and contract with the local boat boys to tow you to and from the starts?  Bene should be cringing with embarrassment.  And yeah, I love it when something is clearly wrong with new machinery and the factory says “Oh, what you are seeing can’t be happening.”  Wankers.

At least that plan would finally solve the water leak as well...:rolleyes:

Link to post
Share on other sites

Qingdaosog,

 

keep the inboard, they are very good to have. And it is a Yanmar, last forever.

I suggest two separate ways forward, do both:

1) get a prop calculation for your boat. Either google "propeller calculation" which will present you with many alternatives, all based about the same basics. Or give boat data as {Lwl, width wl, speed (~5 knots?) and so on.} and then I and many others can make a first calc - it is very easy to do.

2) Look around if you can borrow a somewhat smaller prop, as 12x9 or something. It is quite easy as well to dismount the prop and mount another, you will need some spanners and a heat gun. Note very carefully how the mount is looking, the axis is tapered and there are some different tapering (inch, m, and then also some older things). Guess you have an 25 mm axis (measure with an accuracy to distinguish from 1") if so it is very likely a modern m taper. 

I too think your prop is too large, whatever Bene is saying. Boat builders usually do not put too much energy into prop selection. there is one rule of thumb which is good to know: 1" in dia corresponds roughly to 3-4 " pitch. Usually one want to have a pitch around 8-10" (for these small boats), more pitch results in more prop walk (lost energy), less pitch gives a less grip in the water ...  I would not be surprised if a 12x9 should work much better for you - and your Yanmar!

//J

Link to post
Share on other sites

As I had started to think about this ... I made a first estimate. Used the calulator in https://www.vicprop.com/free-propeller-sizing-calculators, but one can use nearly anyone (EU Bloke's is probably better). Result is, a 2-blade prop (which is what you should have)  should have the dimension 12x9, see the inserted pictures

Note: My input data are not fully correct, probably a bit optimistic. You might have more than 1 bearing (probably 2), and so on. Taking this into account the prop might even be somewhat smaller (the calc pointed toward 12.2" x 8.62, so maybe you should be better served with a 12 x 8, engine will not be overloaded with 12x8; still pitch is not that essential).

first input:

input.jpg.0ac8e9da6aa797efae660f172efdafd7.jpg

 

then outputs:

535358664_firstoutp.thumb.jpg.8cd3306c8803070083a14125510bf86b.jpgsecond.jpg.8a32290eed45ee5bdb6da96fa9c822b0.jpg

 

//J

Link to post
Share on other sites
1 hour ago, Jaramaz said:

As I had started to think about this ... I made a first estimate. Used the calulator in https://www.vicprop.com/free-propeller-sizing-calculators, but one can use nearly anyone (EU Bloke's is probably better). Result is, a 2-blade prop (which is what you should have)  should have the dimension 12x9, see the inserted pictures

Note: My input data are not fully correct, probably a bit optimistic. You might have more than 1 bearing (probably 2), and so on. Taking this into account the prop might even be somewhat smaller (the calc pointed toward 12.2" x 8.62, so maybe you should be better served with a 12 x 8, engine will not be overloaded with 12x8; still pitch is not that essential).

first input:

input.jpg.0ac8e9da6aa797efae660f172efdafd7.jpg

 

then outputs:

535358664_firstoutp.thumb.jpg.8cd3306c8803070083a14125510bf86b.jpgsecond.jpg.8a32290eed45ee5bdb6da96fa9c822b0.jpg

 

//J

Thanks for your trouble Jaramaz. This forum is so helpful. I did try  the Gori calculator and they recommended 12.5 in x 8in. That's not far off my current 13 x 9 it seems.  But another calculation.would be the 35 amp  alternator. I suppose on a small engine of 9hp that will take a significant percentage of the power while recharging the batteries? 

Link to post
Share on other sites
3 hours ago, Qingdaosog said:

  But another calculation.would be the 35 amp  alternator. I suppose on a small engine of 9hp that will take a significant percentage of the power while recharging the batteries? 

If your battery is not fully charged and if you have a large battery bank.  Otherwise, no. Your 35  A generator will not give 35 A for more than some few seconds, then it goes down very fast (I have a 100+ A generator, 450 Ah 12 V lead batteries and after just some few minutes of charging goes down < 10 A.). 35 A x 12 V = ½ hp (about).   All in all, no the generator is probably not the issue.

But I agree that it is strange if a slightly overdimensioned prop should cause the problems you describe. Might be something else ...
- when engine is turned off, completely, and gear stick is in neutral - then you should be able to turn the axis. It should be easy and smooth. Does it?
- when gear stick is in neutral, what happens when your increase engine rpm? smoke? any problems not to rev up? does it go up in rpm fast or do you have to wait (seconds, but still) until it has reached the higher rpms?
- black smoke ... happens when the engine does not get sufficient amount of air. A diesel consumes a surprisingly muchf air. Guess the engine has an air intake which is removable - do that (easy done) and look inside - is there anything blocking air?  there is probably a simple foam rubber air filter - clean that (you can test running without it, it is not necessary).  see to that there is very good ventilation so the engine can get air
- if there is anything around the prop, as a plasic bag or a line or ... then one gets the same as you report (has this been mentioned?)

 

And then this about a rpm instrument. There is probably a sensor at the engine already (?), if so you just need an external instrument. Such you can get for $10-20. There are also separate rpm equipment (for diesels) which may be somewhat more expensive but still very affordable.
On the other hand there is not so much use of it (your can listen to the engine); I would not bother with such.

However, if there is no amp-meter I recommend one such. Maybe also a Volt-meter, there are combo instruments. even if you can start the engine by hand, it is not fun, not at all.

//J

 

 

Link to post
Share on other sites

I have the same 1GM10 in a 5600lb 30' Figaro, driving a 13"x11" two blade folding Martec prop.  I also don't have a tachometer, but I can run it at 6 kts without issues at likely around 3200 rpm.

Do you have water flow?  Should be a pretty steady flow above idle.  The 1GM will make significantly less power with no water flow. I had an impeller fail and power dropped off quickly as it started to overheat.

Link to post
Share on other sites

Very good input from everyone thanks. I love this forum.  I am now  thinking it's more likely an engine issue too. We will be pulling  her out for the winter in about 4 weeks and then I can see if the transmission is stiff and the alignment ok . There is an electric fan to suck out fumes and presumably pull fresh air into the engine compartment. That's not working so maybe the quality of the air entering the engine is also poor. Clutching at straws but sometimes silly things can have consequences. Good old Murphy and his law. 

Link to post
Share on other sites

As mentioned above, first check that the engine is running OK in neutral: full revs and no smoke, and then that the prop shaft turns easily.

Next fuel (sounds OK) and air (air cleaner).

Link to post
Share on other sites

Q, some of these tests are best done while in the water. Do not postpone, even if it is tempting.

test your engine in neutral - any smoke? at full revs? (for this the engine should not be cold, you will need the water cooling).

check air filters, run the engine without the foam thing (if there is any); the foam is not necessary (just good to have).

You must understand that you have a responsibility here - we want to know ^_^

 

BTW, if you are winterizing the most important actions you should (must) do is changing engine oil and oil filter. to do that the engine should be "hot", ie run it for ½-1 hour before removing motor oil (the oil will be easier to extract when hot). Follow the manual!  
If you have fresh water cooling (hope so) then just check so there is some kind of anti-freeze in the fresh part (use to be some kind of glycol). If not, fill some such and let the engine run for some minutes. When lifted and parked empty the sea water, remove impeller. 

//J 

Link to post
Share on other sites
17 hours ago, Qingdaosog said:

  I am now  thinking it's more likely an engine issue too.

I thought it was a new boat?

I've never even heard of issues with a new Yanmar let alone suffered any.

Link to post
Share on other sites

Yes new boat this year. Been busy with other unfortunate issues so only just turning attention to the engine/prop. It's a really good sailboat.Everything  I hoped for when sailing.   Such a shame that it was marketed before wrinkles sorted out. Covid and the weird relationship between Seascape and Beneteau definitely not helped. And the local nominated dealer here is  also overwhelmed. Hence I really appreciate the SA forum input. 

Link to post
Share on other sites

There was a thread about issues getting new 2YM15s to rev last year - maybe useful? 

9HP should be ample for that boat. My Ross 930 was bigger, heavier, and with a 30 year old, 8HP Yamaha outboard I never felt the need for more power.

Link to post
Share on other sites
On 10/18/2021 at 12:51 PM, Irrational 14 said:

My Lumbo 32 will do 5.5-6 knots/3200rpm all day in a flat seaway/light air. I have the same Yanmar 1gm10 and my boat weighs 4700lbs. I run a Flexofold prop.

I have a flexofold and my lumbo will do 6.8 with that engine. the previous prop which was a martec only got us to about 6.

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...