1GM10 Installation in C28

[dgri...@gmail.com]

Hi All,

I'm in the process of installing a Yanmar 1GM10 to replace the old YSE8 in my C28.

I picked up the low hours 1GM10 secondhand for a good price, including all the peripherals (exhaust system, fuel tank, prop etc) and will do the install myself. The YSE8, while still running OK, vibrates the boat badly and is noisy, smelly, oily and heavy. I've pulled it out of the boat and cleaned it up, and at this stage could still put it back in. 

I'm keen to install the 1GM10 however and have been contemplating the modifications required for the engine bed. The 1GM10 mounts are further apart for a start so the engine bearers will need to be cut out and new ones glassed in. After making a template for the 1GM10 and offering it up to the driveshaft it appears the rear engine mounts will barely clear the tuck in the bilge, let alone leave room for a bearer. Options are to move the engine forward about 4" requiring a new longer propshaft, or source low profile engine mounts to provide more clearance. I did think of flipping the rear engine brackets upside down, similar to the YSE8 install however the engine mounts for the 1GM10 wont fit an inverted bracket, so not an option.

Before I start cutting out the old engine bed I'm keen to get feedback from anyone with a 1GM10 installed in a C28, specifically about the engine mount/engine bed arrangement.

regards David

 

[Maeling]

Big job - Many days/weeks of planning and a couple of days to do the job.

I can't give explicit advice.  For Maeling - 40+ years ago (the engine I used is long out of production) 

I made 2 vertical fore and aft beds from doubled 13mm ply with perhaps an internal width 25mm wider spacing than required.  I then got  in with my disc grinder and scurfed the inside of the hull where the beds were going to sit.  I gave the beds a 25mm clearance from the galvanised angle iron brackets on each side and bolted the engine mounts to the brackets.  Then all you have to do is drop the engine in!

I gut-busted my relatively light Drofin diesel in twice.  For a 3rd Act, I'd got a barge  with a Palfinger !!

About 3 years ago, I gave in and got a Beta 15hp. So glad - water-heat exchanger cooled, adequate power for a C29.

Keep on having fun - Geoff

[Maeling]

Big job - Many days/weeks of planning and a couple of days to do the job.

I can't give explicit advice.  For Maeling - 40+ years ago (the engine I used is long out of production) 

I made 2 vertical fore and aft beds from doubled 13mm ply with perhaps an internal width 25mm wider spacing than required.  I then got  in with my disc grinder and scurfed the inside of the hull where the beds were going to sit.  I gave the beds a 25mm clearance from the galvanised angle iron brackets on each side and bolted the engine mounts to the brackets.  Then all you have to do is drop the engine in!

I gut-busted my relatively light Drofin diesel in twice.  For a 3rd Act, I'd got a barge  with a Palfinger !!

About 3 years ago, I gave in and got a Beta 15hp. So glad - water-heat exchanger cooled, adequate power for a C29.

Keep on having fun - Geoff

On Thursday, April 10, 2025 at 6:31:57 PM UTC+10 dgri...@gmail.com wrote:

[MrSeaDragon]

Hi David, 

Well, not a C28 and not a 1GM10 but a very similar situation as when I put the 3YM20 in my C29. I couldn't get the back of the engine low enough, and couldn't move it forward far enough, to get enough room for the existing brackets to clear the hull. 

My solution, as well as new rear bearers, was to make new rear engine brackets (as in the ones above the engine mounts, as opposed to bearer brackets below the engine mounts). They were not only higher, but also wider. This provided enough room, but even as it is the back outer corner of the bearer bracket is only 10mm off the hull.

If you haven't seen my refit album have a look at a few of the photos from this one for the bearer brackets : https://photos.google.com/share/AF1QipP3q4uz96sGtqd6nikkmQc-3G-2jBJT02odI8XvHjC3_C68jzXRJCVLzDZh-P1HGQ/photo/AF1QipNQUgIXy0o2qdgUhkDzVrxmhFdkF3ajliQMs2I4?key=WHV4akI4YVBYMGpVWjhvUmY0T0VaT3hpbzNocVVR 

and this one where you can see the engine brackets : https://photos.google.com/share/AF1QipP3q4uz96sGtqd6nikkmQc-3G-2jBJT02odI8XvHjC3_C68jzXRJCVLzDZh-P1HGQ/photo/AF1QipOCc68Jau9z8e4k72SrlUBvcspybmqvvN_W0GHg?key=WHV4akI4YVBYMGpVWjhvUmY0T0VaT3hpbzNocVVR 

Hope the links work.

Kind regards,

Greg

C29 Sea Dragon 

[Maeling]

Thanks Greg

[dgri...@gmail.com]

Thanks Geoff and Greg for your feedback.

I was planning to proceed as you described Geoff but was stumped by how to get the rear mounts low enough for the drive flange to align with the propshaft.

Greg, fantastic job on the rebuild. Thanks for the link to the photos. They have given me some ideas, especially with facing the bearer brackets outwards rather than inwards. It looks like I will have to also fabricate new rear engine brackets to provide sufficient clearance for the flexible mounts. I was initially reluctant to go this way in case it affected the propshaft thrust dynamics, but I don't really see any alternative without moving the engine forward considerably. 

Still keen to hear from anyone with a 1GM10 already installed in a C28 (or even a 2GM20 which has the same rear end footprint) . Looking through the register there are a couple that I can see, including KOTARE, which coincidently used to be my dad's boat 40 years ago.

Geoff, please can you update my boat HUAHINE's details in the register when you get a chance? Registration AZ195Q , now moored in Mission Beach, QLD

regards

David

[Graeme Lock]

Hi David;

A couple of things that may help:

1. The 1GM10/2GM20/KM2P variants have the same dimensions as the older 1GM/2GM/KM2A family, so any of the many C28 owners who have these older ones (like me - 2GM/'KM2A) might be able to help.

2. When I replaced Shakti's mounts about 10 years ago, the lowest profile ones I could find were the Trelleborgs as per the attached pdf. Even with those, there is so little clearance that I had to dispense with the lower lock nut and use shims for height adjustment. I can't begin to describe what a pain that makes it to adjust the alignment, but I had no choice and have gotten a bit better at it now.

Good luck with your project, Graeme

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[David Grigg]

Hi Graeme,

Thanks for the tip re the other engines, and also the Trelleborg mounts. I was starting to shy away from replacing mounts as they all seem to be so expensive and didn't gain me much clearance anyway, but will check out the Trelleborgs. 

regards

David

To view this discussion, visit https://groups.google.com/d/msgid/compass-yacht-group/CAKNX5oDB%3DkACM%3DySuKBQo2tB3LoQQTTHY4voS%2BJGPxXoBy-WaA%40mail.gmail.com.

[Graeme Lock]

This might help.

To view this discussion, visit https://groups.google.com/d/msgid/compass-yacht-group/CAPXwvhFhTT-QWJ0BVt--jyK9%2BV%3DTXHub3KD5es5tVNgoSv7ruw%40mail.gmail.com.

[Maeling]

Fixt? Might have to go back to my old dB

Geoff

[Maeling]

We're all getting that bit older and less flexible.

G