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post #257 of Old 01-01-2013
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Re: Production boats- justified bias?

Originally Posted by JonEisberg View Post
First thing that catches my eye in the comparison of those two boats, is yet ANOTHER trend I don't like in many of today's production boats... (grin)

Namely, the increasing use of saildrives... The principal advantage of them is to the builder, as their installation greatly simplifies the build - but there seems little to recommend them over a conventional shaft drive to the end user, mostly what I see are downsides, that are not overruled by their very few advantages ...

Needless complexity - why induce 2 right angles, into a drivetrain that could otherwise be direct?

BIG hole in the bottom of the boat, the potential for corrosion issues, and in some saildrives, the boat needs to be hauled simply to change the unit's gear oil... that's just insane...

Their typical placement further away from the rudder greatly reduces the effect of propwash against the rudder, making them less effective in close-quarter, slow speed maneuvering...

I'm a big believer in having the prop as accessible as possible from above the water, or as close to the end of the boat as possible... If you've ever had to dive on a prop to clear it of a line, or similar, you will greatly appreciate the difference of having to do so on the 2 boats pictured above... The location of that saildrive would make it very difficult to free-dive on it, much more so than the prop on the Beneteau... One of the downsides of today's boats with very beamy aft sections, getting to the prop - by either diving on it, or using a hook knife on a pole - is gonna be a lot more work on many modern boats, than on a boat like mine, with much finer ends...

I'm actually able to at least touch my prop without even putting my head underwater, so it's very easy to dive on, and in the couple of times I've caught a wrap on the prop, I've always managed to cut if free from the cockpit, without even having to put my dinghy over the side...

When I had the first boat with a saildrive, more than 10 years ago, I had about the same distrust as you and for the same reasons. If I could I would have the same boat with a conventional drive. At that time the boats that had saildrives were a minority and not as today where almost all use it, including for instance Halberg Rassy and many very expensive boats. As you can imagine in what regards to expensive boats they use it because they consider it a better system and I don't think it is a cheaper one anyway.

From one engine brand using Saildrive (Volvo-Penta) you have now all brands using saildrive as the most common system by far.

10 years after I understands better the advantages and become assured in what seemed to be the disadvantages. While I have heard of several boats sunk with problems with the conventional system (shaft broken, ingress of water) I don't know of a single one that went down with a faulty saildrive ring and are tens of thousand using it.

The main advantages are absence of vibration, silence, less maintenance (one time each 7 years) and completely watertight.

The advantage you refer of having the propeller near the surface will turn quickly in a disadvantage trying to come out of a port with big waves or in any other situation you need the engine with big waves and no wind. Those conditions will bring the propeller in and out of the water resulting in a very reduced efficiency and potential mechanic problems.

That's not by accident that today the actual successor of Mark's boat on Beneteau (the 41 and all the others) use sail-drive.

You are right regarding the disadvantage of maneuvering in port but today's boats with skinny keels turn in their own length and besides, at least here, the normal final approach is in reverse to have the boat with the bow to the outside and in that situation you have no advantage having the propeller nearer the rudder.

Anyway I believe that the standard will become quickly the two rudder system that has many advantages (not only for boats with a fat transom) and that would make completely irrelevant in what concerns maneuvering to have or not saildrive.

I believe we will see more and more the use of saildrives that can turn around giving you almost for free a stern thruster. The diminished maneuverability in port that the two rudder system provide would make necessary or at least very desirable a solution like that. Those saildrives are already used as part of the system on modern docking solutions for bigger boats.

I see that you have a Brunton's propeller. I had also one and they are great but I am a bit surprised to see a 3 blades in the one in your boat. I am sure it is correct but I am curious. Your boat needs more than a 30hp engine?



Last edited by PCP; 01-01-2013 at 05:00 PM.
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