Volvo MD2020 removal in water - Bavaria 31

[reystos]

Hi everyone!

I have just had the pleasure of running my engine without oil shortly after going into sea after winter. By the time I saw the warning light it was 30 minutes too late. It ss cooked now and the boat is in the marina.  Do you have any experience of removing it while in water?

I have disconnected everything electrical, water and fuel wise. Seacock closed. But am curious whether I should support the saildrive while separating it from the engine and holding is supported while the engine goes out.

Thank you!

[tiger79]

But am curious whether I should support the saildrive while separating it from the engine and holding is supported while the engine goes out.

I wouldn't remove the engine from the saildrive while the boat is in the water.

[Yngmar]

The saildrive diaphragm can technically support the weight of saildrive and leg, at least temporarily. You'd definitely want to support it at the front after removing the engine.

That said, I would be very nervous about doing this in the water too. One wrong move and your boat will sink almost instantly, and insurance would likely argue that this was grossly negligent. Probably not worth the risk unless you can't get a haulout where you are.

[reystos]

All good, problems solved. Old MD2020 went out, new D1-30 went in. Volvo makes an adapter kit specifically for retrofitting a D1-30 onto a 120S saildrive. It replaces exactly the MD2020 and sizewise the two engines are exactly the same. Even the engine/hull mounts are the same. 

This way I got to keep my saildrive and diaphragm (that had just been replaced anyway), boat stayed in the water during the whole process. It was done within one afternoon. Saildrive remains connected to the rear mount, the diaphragm also holds it while the new engine goes in.
Now I need a new prop 

[symphony2]

Yes, the shaft revs will have gone down from 1500 to 1330 and 10 more hp so you will need to change the pitch. Good time to invest some of your savings in a Flexofold 2 blade

Speak to Chris here  darglow.co.uk who will calculate the size for you. Just make sure you tell him that you have the D1 30 and 120.

BTW interested why you chose the 30. Way OTT for the boat. You will not be able to use all the power with that waterline length and displacement (3600kgs). you only need 18hp to achieve hull speed and the 20hp engine and probably a 16*11 prop would give you 7.35 knots and would have been more than enough. You really don't need the 30 until displacement goes over 4500kgs and even in my 33 at 5500kgs exceeded hull speed at just under 8 knots.

[reystos]

Although it is not very obvious, I agree with you. The numbers were supposed to make sense, based on arithmetic calculations and I went through them multiple times before the engine mishap which led to the upgrade.  Got a larger prop to see if I could make it cruise at 6knots without blowing it to bits. No big improvement.
It is very possible that out of the 19hp on the MD2020 some of them became seahorses over time.
In theory should be able to go near or above 3200rpm or at least hold itself at 2800 for a while. In reality, it got dangerously loud and that made me feel very nervous. The md2020+120S saildrive was always underpowered on my boat, even on the larger pitch prop. It just did not make enough power to cruise comfortably as fast as slightly larger vessels (33-34ft). Even on a freshly painted keel. To reach 5.5knots it would take 2400rpm and some waiting. In rough seas or opposing current it would really struggle. Above 2600-2700, just would refuse to go. With a bit of sealife on the propeller, 2500-2600 was the hard limit.

Given the external size of the engine is the same, fuel consumption almost the same, why not go a step larger? Having more power and not using it probably beats not having it at all.

[symphony2]

Suspect your 2020 was well down on power as when hew it would easily have achieved hull speed with a standard prop. Of course in heavy weather a light boat with high windage like yours would be hard going however much power you throw at it. Don't know what prop you have, but my D1 30 came with a 16*13 fixed 2 blade, but I never used it as I fitted a 16*11 Flexofold.

You should be able to get 5.5 knots in flat water at around 2000rpm and as suggested earlier close to 8 knots at over 3000rpm, by which time you will be digging the stern in as that is well over hull speed.

[reystos]

Would that be on a 130S saildrive rather than the 120S I am using now? Their drive ratio is quite different, making the 120S much shorter still.

[symphony2]

Using the vicprop calculator you need a 17*12 2 blade - which is a huge prop compared with your original which would have been a 15*10 or maybe a 15*11

[reystos]

Thank you! It will be either that or a 3bladed prop.

[symphony2]

You really don't need a 3 blade. There are no restrictions on diameter with the saildrive and you don't want the extra drag of 3 blades. As i said you have far more power than you need and the important thing is to keep the engine loaded when cruising which the bigger 2blade will do.