SD50 Saildrive

• The SD60 has a different footprint and has two securing bolts at the aft end which are not on the SD50. You will need to ensure that you have the necessary metalwork in the bearers and holes drilled and tapped to take these bolts. My 2010 400 didn't so I had to buy an adaptor plate from Yanmar (just over £1,000). The plate also comes with plates for the engine mounts so that the whole engine is raised 12mm. This required new, longer M10 mounting bolts for both the SD60 and the engine mounts to bearers.
• You will need a new drive coupler plate for the engine. I couldn't source one in the UK or Europe but founds lots in the US ($400). 
• The gear selector lever is on the opposite side to the SD50, resulting in the throttle lever operating 'back to front' (ie. what was forward gear became astern!). I had to switch the gear cable to the other side of the throttle lever.
• The gear selector rubbed the exhaust hose, so I had to move that slightly.
• There is no space in the 400 aft of the saildrive so it cannot be tilted to the stern for removal - the 430 might be different. I had to split the SD50 in two for removal, with the leg removed from underneath and the transmission from the top. The SD60 needed the propshaft to be removed, which required the draining of the oil (it comes filled from the factory). I was then able to drop the SD60 in vertically (with engine removed).

Otherwise straightforward. Engine had to be removed completely and I needed to cut an additional access panel in the aft starboard cabin to enable alignment of the shaft to the saildrive.

Firstly, although the forums can be great there is a tendency for them to detail 'the sum of all fears'.  You read of the troubles others have had and understandably worry about your own situation.  Yet you'll never read about the far greater number of others that have never experienced the same malfunctions.  With specific regard to the SD50, yes; the cone clutch is a well known PIA that needs regular lapping - but there's a fix for that with the upgrade kit for about $750.  Mine has worked flawlessly for many hundreds of hours since upgrading and the available literature suggests this will extend the life of the clutch well beyond Yanmar's recommend for replacement at 2000 hours.  Even if you did replace the clutch, the cost isn't that great.  Much of my concern for my SD50 was a result of poor professional advice verging on the negligent.  I got a 2nd and confirmatory 3rd opinion and it turns out I needn't have worried at all.  Mine has now done 2000 hours and is running perfectly well.

My second point is the familiar 'if it ain't broke don't fix it'.  I went through a very similar thought-process to you so I understand your situation but if your SD50 is running fine - and given the option of the well-regarded upgrade kit - why go to all the hassle and expense that Martin has helpfully detailed?

With regard to the Silic 1, I changed to that 3 years ago after I had the SD leg epoxied as per Yanmar's recommendation; the difference was remarkable with much lower levels of fouling.  However, to put that in context, while Portsmouth Harbour is among the worst locations in the UK for heavy fouling we actively cruise for 5 months a year covering a lot of miles, so the way a boat is used might explain the disparity in the results you found.  

That all said, if you choose to save your money by not getting the SD60, your boat will soon figure out another way to reduce your bank balance by at least the same amount.

Good luck!

Iain

I have decided to keep the SD50 and refurbish the seals etc. and just stay on top of the maintenance. Also thinking I will source a spare lower leg that’s in good condition. 

Fingers crossed on the Silic One. 

Again - good luck!

Anyone out there that has self performed the sd50 removal in a 430?