Engine Mounts

Never used them, but I do know that Yanmar offer at least two different hardnesses for engine mountings. My new Yanmar 3GM30F had vibration problems on the softer ones, improved when I changed them for harder. It was a long time ago and I don't remember exactly what I did but it may be I have harder ones in the aft position, softer forward.
 
Picking up on Vyv's reply, it is true that my 3YM30 has different load mounts from front to rear, this will definitely have an effect on vibration felt through into the hull, but it may also have an effect on the life of brackets and flanges cracking due to harmonic vibrations increased forces.
 
FullCircle said:
Picking up on Vyv's reply, it is true that my 3YM30 has different load mounts from front to rear, this will definitely have an effect on vibration felt through into the hull, but it may also have an effect on the life of brackets and flanges cracking due to harmonic vibrations increased forces.
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Yanmar do several hardnesses of mounts and they are stamped with a number - 50; 75; 100; 200 etc. Present boat has Yanmar 2GM and it has harder 100s at the front and softer 75 at the rear
 
I don't think the quoted numbers of 100, 200 can be Shore A durometer values. AFAIK the scale only goes to 100. I have worked a lot with elastomers of 98 Shore A, they are right at the limit of what is possible in an elastomer (rubber) Even at 98 they are verging on plastic with quite a lot of compression set. I would expect engine mounts, which need plenty of elasticity, to be more like 40 - 60 Shore A. http://www.bluerealmstudios.com/2009/02/25/understanding-shore-hardness/
 
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