Raven Yacht Owners Association

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Replacing Engine


Re placing a Volvo 2002 with a Volvo D1-30 ( Contributed Keith Murray)

What motor did the boat originally have?  18hp Volvo 2002

What was it replaced with?    28 hp Volvo D1-30

Any significant problems? No    

Saildrive or shaft driven? Saildrive for both

What modifications if any had to be made to engine mounts etc?    Very little.  The back of the half round support had to be lowered about 20mm to clear the sump.  I was able to do that myself.

Were any accessories eg compressor ,fitted with motor?      None.  I will not tolerate compressor on motors for fridges as it is stupid to run a 28 hp motor just to drive a freezer compressor.  Electric fridges and freezers are trouble and maintenance free and last for ever.  The new motor has a 110 amp alternator with reasonably intelligent regulator and I have solar panels.

Salt or freshwater cooled?  Original motor salt water cooled, new motor fresh water cooled

Approx cost and date of fitting? Feb 2009, $20,000 for motor, saildrive, 3 bladed feathering prop and installation.

 I have not needed to repair anything on the motor and did not expect to do that.  I did have to move the header tank for the coolant from its manufactured position and can send a photo if that is of interest.  We also modified the back of the companionway steps to allow room for the front of the pulley for the v belts.

Basically the new motor went in the old hole and is lighter than the old one.
The 28 hp motor is overkill but as it was only $500 extra I said ,"Why not."  The boat does not go faster.  At full revs it still does 7.5 with the boarding platform level with the water.  In calm water and clean hull 2100 revs gives 6 knots.  The old motor achieved that at 2200 revs.  The benefit is that I now have a 17 inch diameter 3 bladed prop rather than a 15inch prop. Thus when at the bottom of Wellington harbour with a 25 knot headwind I apply 2300 revs and come home to Seaview at 5.8 knots.  The old motor would have had me hovering below 5.
The problem is that 2200 is the bottom of the cruising rev range.  It will run slower and is very economical at say 1950 revs with the speed at 5.7 knots.  But that is too slow for the engine to work properly and get to operating temperature.  After 5 years the exhaust outlet is bunged up. 
At 2200 the speed gain is negligible but fuel consumption goes from 1.5 to 2 litres an hour. Any increase in engine speed achieves little increase in boat speed for a lot more fuel.  At 2500 revs the fuels use is 3.5 litre per hour up 40% for 16% increase in boat speed.  Note that the fuel graphs suggest that 2200 revs uses 2.4 litres and hour.  I seem to do a bit better than that and it may be that the engine could swing a prop with more pitch.  I think it is 17x15.

Replacing 1GM Yanmar with 2GM ( Contributed Tarragon , Chris Barton)

 What motor did the boat originally have? 8 hp Yanmar

What was it replaced with? 2gm20  Yanmar

Any significant problems? No 

Saildrive or shaft driven? Shaft 

What modifications if any had to be made to engine mounts etc?  No

Were any accessories eg compressor ,fitted with motor ?. None

Salt or freshwater cooled? Salt

Approx cost and date of fitting? 1990s 

Any tips, things you would have done differently etc. anything we should know. I did not replace the engine myself was done by previous owner. I replaced the 2 bladed prop with a 3 blade fixed after some slow trips up the harbour against wind and tide. The motor is rated at 16 hp at full revs 3000rpm will do 6 knots in flat water although the boat stern in being pushed down, only slows to 5 knots at 2500 and is far more a comfortable ride.  I suspect the design of the raven 26 would not really gain any more speed benefit from the addition of more than 15 hp, probably just continue to drag the stern down into the water...in saying that I am very glad to have the additional horses, the boat can basically turn  in its own length, Being salt water cooled means a simple setup but probably living on borrowed time with the inevitable corrosion going on inside the engine block.



 Replacing old style 9/10 hp Yanmar with 1GM10 ( contributed Kellys Eye,Scott Hudson


 What motor did the boat originally have?

The original which was a large 9 or 10 HP Yanmar.

 What was it replaced with?

Yanmar 1GM10 – a single cylinder 9HP.

 Any significant problems?

Not a problem as such but as the new engine rotated the opposite way to the original, a new prop was required.

 Saildrive or shaft driven?


 What modifications if any had to be made to engine mounts etc?

New mounts were installed. Also a new dripless shaft seal replaced the old greased twine stuffing box.

 Were any accessories eg compressor ,fitted with motor?


 Salt or freshwater cooled?


 Approx cost and date of fitting?

Engine $8,000. Total job $13,000. I had money then.

 Any tips, things you would have done differently etc. anything we should know.

Yes. The original engine included a small diesel tank on top that was manually gravity filled from the main tank under the cockpit  seat. The new engine didn’t have this tank. It was fed directly from the main tank.

I learned the hard way one day that letting the tank get below half full then having the boat heal in a strong wind, would result in air being sucked instead of fuel. I did this twice – and bled the fuel system twice - in a blow and big seas just off Mana (Porirua), before I worked out what was happening.

 Another small regret.  In hindsight is that I didn’t get the 18HP engine for extra capacity to run a compressor.


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