Conversion from saildrive to outboard?

Outboards or inboards, electric, fuel or diesel, cavitaion and torque talk
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dennisail
Posts: 61
Joined: Tue Feb 19, 2013 1:42 pm

Conversion from saildrive to outboard?

Post by dennisail » Sun Sep 21, 2014 10:46 am

I have the shits with my 3GM30 and SD20s inboards already. How much would you estimate the cost (excluding labour) to change to outboards including price for controls hardware and suitable outboards?

The boat is a 43 foot Crowther 226A, weight around 8T. Currently has 27hp engines with folding props and does around 9K downwind in 10K of true wind and 8.5K upwind against 15 apparent. Can do 6k on one engine and medium rpm.

What outboards would be a good match? Would I get away with 20hp or would I need bigger?

Im thinking of going a kickup rudder conversion and getting rid of the diesels in one go. Do I have enough room behind the back beam? I would try to do a 44c style setup as its the best way I have seen.

What would the old engines be worth? All in good condition 1400 hours, 3GM30s with SD20 saildrives, 3 blade volvo folding props, spare 3 blade fixed and one high out put alt on one engine.

I know diesels make the boat worth more, but I like my boat and the only box it did not tick when I purchased it was shoal draft beachability. I beached it on the weekend on the rudders, which seemed to work fine but its still not ideal, and with the diesels starting to irritate me its got me thinking.
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Bedar Crowther 226A.JPG

dennisail
Posts: 61
Joined: Tue Feb 19, 2013 1:42 pm

Re: Conversion from saildrive to outboard?

Post by dennisail » Mon Sep 22, 2014 10:55 am

GOPR0026.JPG

Romeo
Posts: 49
Joined: Sun Nov 09, 2008 10:32 pm
Location: Western Australia

Re: Conversion from saildrive to outboard?

Post by Romeo » Mon Sep 22, 2014 6:58 pm

Have you thought about getting rid of the dagger boards and putting on mini keels it would be a lot cheaper.
Cheers Romeo

dennisail
Posts: 61
Joined: Tue Feb 19, 2013 1:42 pm

Re: Conversion from saildrive to outboard?

Post by dennisail » Tue Sep 23, 2014 2:52 pm

No. That would not give me much benefit over what I have now when it comes to beaching, but it would make the boat a lot slower and make the draft even deeper, plus I would still have the diesels which I am not all that fond of.

Smooth Cruiser
Posts: 583
Joined: Thu May 11, 2006 1:51 am
Location: Brisbane

Re: Conversion from saildrive to outboard?

Post by Smooth Cruiser » Thu Sep 25, 2014 12:07 pm

I think 20HP outboards is verging on too small for that boat. I have a 44' Schionning with 2 Honda Bigfoot 20 4 strokes. Pushing into a headwind I run out of go very quickly - only making a few knots in anything over 20knot headwind. Also the thrust in reverse is very poor making it difficult to pull the boat up or reverse into the wind when berthing. I would go larger except these are the largest motors that will fit in my wells. I have the largest propellers that will fit this engine already.

The problem is really the gearing - in some regards I think the Yamaha 9.9 hi-thrust motors (old style) were more practical on this sort of boat than the Honda 20's are. Unfortunately the new Yamaha 9.9's don't have the same reduction gear and hence don't push the big propellor that the old ones did.

I would think 2 x 30's might be a better size but choose the lowest gearing and largest propellor combination that you can find - this is much more important than top end speed.

My outboards go up and down vertically in the wells whcih is a great arrangement but requires a bit of a cunning leg extension to seal the hull when pulled up. My wells are in teh hulls not pods, so similar to what you would end up with once you pulled the diesels out.

While outboards are light and easy to replace and can be easy to remove for maintenance, don't underestimate the benefits of diesels, that they are very reliable, have heaps of grunt and provide large alternators to keep your batteries charged.

Good luck whatever way you go!

dennisail
Posts: 61
Joined: Tue Feb 19, 2013 1:42 pm

Re: Conversion from saildrive to outboard?

Post by dennisail » Thu Sep 25, 2014 4:17 pm

Thanks. After considering the costs and hours involved, I think it does not make a lot of sense to swap this out.

I think I will cut 100mm off the rudders and add strong small wings to the bottom. That way they won't sink into the sand (and the sail drives won't come close to the bottom). It will have a little less draft and from all I have read winglets on keels/rudders improve the efficiency of the foil making it seem like the keel/rudder is much bigger than it is.

So it might be a good compromise and easy to do. I will just set the daggers to the draft of the rudders to protect the drives from obstacles until I have found a suitable place to beach.

dennisail
Posts: 61
Joined: Tue Feb 19, 2013 1:42 pm

Re: Conversion from saildrive to outboard?

Post by dennisail » Thu Sep 25, 2014 4:37 pm

I agree there is a good benefit diesels have in fuel economy, and the ability to swing the correct size prop to get the job done. I don't think they are all that more reliable than an good outboard. Or at least the extra reliability is offset by being harder to work on. Outboard mechanics can be found in even the most remote places where the local boats are outboard powered. Solar is so cheap these days the extra power from the alternators is hardly a benefit.

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