Saildrives vs Inboard

[mglonnro]

Originally Posted by a64pilot

Pros for the manufacturer?
However one assumes if you can afford either new, then buying a replacement sail drive every few years is no big deal, plus I don’t believe many new boat buyers keep that boat for too many years.
Many buy new cause simply put they can afford it and trade up every few years like they do their car, cause they can afford it.

Shaft drive is cheaper to own and maintain, but if your buying a new Gunboat, that’s likely irrelevant.

I have to admit I don't know why I would have to change the saildrive every few years. On my previous boat I did change the whole engine (including saildrive), but it was 22 years old and the saildrive was working well. The engine, not so much

"Don't worry about the budget, just make sure you use an inferior propulsion system!"

... said no Gunboat buyer ever.

WELL.

Don't take me too seriously, I understand there are good arguments for the shaft.

[Open-d]

Originally Posted by mglonnro

I think all new Gunboats and Outremers come with saildrives. To me, that is good evidence that the pros outweigh the cons.

Which pro or pros carried the day for those manufacturers.

[redneckrob]

Originally Posted by a64pilot

Pros for the manufacturer?
However one assumes if you can afford either new, then buying a replacement sail drive every few years is no big deal, plus I don’t believe many new boat buyers keep that boat for too many years.
Many buy new cause simply put they can afford it and trade up every few years like they do their car, cause they can afford it.

Shaft drive is cheaper to own and maintain, but if your buying a new Gunboat, that’s likely irrelevant.

Just to be clear, saildrives in practice haven't required replacement every few years as a matter of course. Certainly a few people have had to replace them, just as a few people have had to replace drive shafts. But it would be a pretty inaccurate view that they are regularly replaced on most or even many boats ever during the lifetime of the boat, let alone every few years.

[mglonnro]

Originally Posted by Open-d

Which pro or pros carried the day for those manufacturers.

Don't know!

Here's a nicely written post about it, however: https://multihullcompany.com/article...s-best-for-me/

[fxykty]

Originally Posted by Open-d

Which pro or pros carried the day for those manufacturers.

Must be cheaper to install as the previous owners of Outremer with the first generation designs designed for shafts. Not sure about the 45, but definitely shafts for the 50 and 55.

They also probably don’t want to ‘waste’ all that hull length for non-accommodations space (yes, the new generation Outremers look wasteful and spacious to us first generation owners).

Bottom line, shouldn’t be a deal breaker if the sail drives are in reasonable condition.

[Tin Tin]

Originally Posted by mglonnro

Don't know!

Here's a nicely written post about it, however: https://multihullcompany.com/article...s-best-for-me/

Yes Phil has been in the Catamaran industry a very very long time and knows his stuff, and note he does talk about sub 50ft cats, it was interesting point that at the time of the article the available sail drives for bigger engines were non existent, so only option was shaft.

[Chotu]

There IS an alternative. The V drive.

[Srah 1953]

Originally Posted by warren2

I have volvo saildrive and you cant attach a rope cutter - big problem

I was thinking of changing from a boat with a Yanmar to which I have attached a rope cutter to a Volvo. So I'm interested to know why you can't with a Volvo.
Please and thanks

[Srah 1953]

Originally Posted by warren2

I have volvo saildrive and you cant attach a rope cutter - big problem

I've just looked up the Ambassador Marine website and they are showing rope cutters for Volvo saildrives, at least for some models anyway.

[Muaddib1116]

Originally Posted by Chotu

There IS an alternative. The V drive.

That looks like it raises up the engine cg quite a bit, unless there's a keel to hide the prop shaft in.

Originally Posted by Srah 1953

I was thinking of changing from a boat with a Yanmar to which I have attached a rope cutter to a Volvo. So I'm interested to know why you can't with a Volvo.
Please and thanks

It is possible, I've seen them. It's very possible that it's not easy though, I don't know too much about it.

[Tin Tin]

Originally Posted by Chotu

There IS an alternative. The V drive.

V drives are often used in large power boats. If that diagram was super-imposed into the rear engine compartment of a 45ft sailing cat say, all I can see are :
1. Engine weight right in the tip of the stern,

2. Inefficient prop angle
3. Working in and around that complicated gear box and shaft drive would be a challenge


but hey, it would probably work - I doubt there will be a clamoring of enough sailors to make a market segment big enough (same as for direct shaft) that would encourage manufacturers to adopt it or even bother with the cost of building a prototype, let alone bench test it, sea trial it, work out a warranty rate etc etc. I think same also applies to the electric drive experiments around at the moment, but that might change with public/customer opinion driving green solutions.

[Dsanduril]

Originally Posted by Chotu

There IS an alternative. The V drive.

I own two of them, not sure I’d recommend them over a saildrive or a straight shaft. They serve their purpose, and I’m not going to throw them away, but...

The stuffing box/shaft seal is under the engine and a royal pain to access, and yet with a shaft drive this is the one piece that is nice to be able access. And if the shaft seal drips the shaft flings saltwater all over the bottom of the engine, rusting out the oil pan.

You can’t install any of the flexible disc couplings because the shaft would put them in tension, and they are all made for compression. Which means you have to be dead on with alignment. But you don’t have easy access to the stern tube to do your sights or check your center.

Those are the things I’ve learned from living with two of them for four years.

[Open-d]

Originally Posted by mglonnro

Don't know!

Here's a nicely written post about it, however: https://multihullcompany.com/article...s-best-for-me/

Thanks, Good article.

[redneckrob]

Originally Posted by Dsanduril

I own two of them, not sure I’d recommend them over a saildrive or a straight shaft. They serve their purpose, and I’m not going to throw them away, but...

The stuffing box/shaft seal is under the engine and a royal pain to access, and yet with a shaft drive this is the one piece that is nice to be able access. And if the shaft seal drips the shaft flings saltwater all over the bottom of the engine, rusting out the oil pan.

You can’t install any of the flexible disc couplings because the shaft would put them in tension, and they are all made for compression. Which means you have to be dead on with alignment. But you don’t have easy access to the stern tube to do your sights or check your center.

Those are the things I’ve learned from living with two of them for four years.

You have them on the Outremer in your profile, just out of curiosity?

[Mystic38]

Well, you have made your mind up so its not clear why this thread,..?

But, anyway, you have presented your opinion as fact, so let me refute the "they concentrate weight to the rear instead of centered" statement.

The weight is where the designer puts the engines.... put them aft, the weight is aft, put them fwd and the weight is fwd.

So, in a condomaran design where the engines are under bunks or in the transom then yes the weight is aft.. however..do you not think that this is factored into the design of the vessel? Boat design is simply an exercise in tradeoffs, and such a configuration gives significant extra internal usable volume..

I own a St Francis 44, where the engines are midships as are the saildrives.. so the weight is actually more balanced than if there were shafts... but again, this has nothing to do with sail drives and all to do with vessel design.. the tradeoffs in this case are reduced usable internal volume to the benefit of narrower hulls, sleek exit and a better sailing design.. in this case, sail drives allowed Lavranos to develop this sleek fast hull... (at the expense of wide hulls and lots of interior volume..a tradeoff i fully accept)..

you or anyone is welcome to not like sail drives, but the reality is that they are nothing more than a tool for the designer to muck about with various layouts and design options.

Originally Posted by Open-d

I would like to discuss the issue of saildrives vs inboards. I am not a fan of saildrives as they appear to be weak and vulnerable. Further, they concentrate weight to the rear instead of centered.

However, they are popular.

Please discuss. Pros and Cons.