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Old 09-02-2016, 11:06   #1
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Saildrive VS Direct Shaft

Hi,

What do you think about a VOLVO engine saildrive or a "not yet known" direct shaft drive on a average size sailboat ( let's say 30-45 ft) coupled with folding propeller?

Difference in reliability?

Saildrive may require additional work, leg's oil changing will require an haul out almost annually, more mainteniance, anode zink both on prop shaft and on the leg, and as far as i know they leaks sometimes between the leg and the hull...And more exposed in case of grounding or semi floating object...(even "protected" by the keel")

The direct shaft maybe more hydrodinamically, more protected, only one zinc to chek, and it could leaks at the bearing throug the hull.

Thanks all
Stefano
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Old 09-02-2016, 14:25   #2
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Re: Saildrive VS Direct Shaft

Saildrives have their enthusiasts.

However, among our friends who have them, all have had problems. One even has gone so far as to make a seal for the hole when it is removed, to save on the costs of days and weeks on the hardstand. We wouldn't have one.

Our friends who built their own aluminium boat have a shaft drive: he's an engineer. He could explain all the reasons for it way better than I can.

Go for the shaft drive.

Ann

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Old 09-02-2016, 14:28   #3
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Re: Saildrive VS Direct Shaft

Thanks...

I guessed it too..direct ,i'm 100% for shaft....Just wondering why so many used boat has saildrive...
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Old 09-02-2016, 14:50   #4
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Re: Saildrive VS Direct Shaft

Quote:
Originally Posted by stefano_ita View Post
Thanks...

I guessed it too..direct ,i'm 100% for shaft....Just wondering why so many used boat has saildrive...
Installation costs and engine placement are the two main reasons boat builders go with saildrives.
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Old 09-02-2016, 15:03   #5
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Re: Saildrive VS Direct Shaft

Quote:
Originally Posted by stefano_ita View Post
Thanks...

I guessed it too..direct ,i'm 100% for shaft....Just wondering why so many used boat has saildrive...
Stu's right, and it's gonna get worse as many of the now newer boats become used, excuse me, previously owned boats.

Drats.

Mine's a keeper!!!
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Old 09-02-2016, 15:22   #6
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Re: Saildrive VS Direct Shaft

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Originally Posted by StuM View Post
Installation costs and engine placement are the two main reasons boat builders go with saildrives.
Thanks...

About engine placement what is the difference?

I saw boat of same dimension, same layout, some with saildrive and some with direct shaft (long about 6-7+ feet) with the aft part going up quite vertical, some with much inclined prop shaft but shorter...

For cost and time installation in a supply chain for sure saildrive win, until the owner get his new boat...
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Old 09-02-2016, 15:24   #7
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Re: Saildrive VS Direct Shaft

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Originally Posted by Stu Jackson View Post
Stu's right, and it's gonna get worse as many of the now newer boats become used, excuse me, previously owned boats.

Drats.

Mine's a keeper!!!
LOL

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Old 09-02-2016, 15:38   #8
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Re: Saildrive VS Direct Shaft

Quote:
Originally Posted by stefano_ita View Post
and as far as i know they leaks sometimes between the leg and the hull...And more exposed in case of grounding or semi floating object...(even "protected" by the keel")
I believe at one of the boatshows Volvo had a fish tank with the seal in it. They had a divers knife through the seal.

My propellor on a shaft is about 15" from the rudder so in close quarters water is directed straight over the rudder giving instant turning forces. Have a think about a sail drive with the prop 2/3rds along the hull.


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Old 09-02-2016, 15:42   #9
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Re: Saildrive VS Direct Shaft

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Originally Posted by Ann T. Cate View Post
Saildrives have their enthusiasts.
Most of them are boat builders.


all things being equal - and if I had the choice- I'd prefer straight shaft.
Not many small cats around with that, so its more a theoretical question.

I remember a Lagoon 500 (called nipper?) sank because the dinghy painter got into the prop which dislocated the saildrive.
We had a similar incident in our previous boat: Ran into a pile of fishing net, cracked the saildrive bed and had some minor leak which required a haulout a few days later.

But: we now have saildrives, too.
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Old 09-02-2016, 15:51   #10
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Re: Saildrive VS Direct Shaft

Quote:
Originally Posted by stefano_ita View Post
Thanks...

About engine placement what is the difference?

I saw boat of same dimension, same layout, some with saildrive and some with direct shaft (long about 6-7+ feet) with the aft part going up quite vertical, some with much inclined prop shaft but shorter...

For cost and time installation in a supply chain for sure saildrive win, until the owner get his new boat...
A good friend has a Hunter e33 with the saildrive. Engine placement? His engine, to me, is in the boat BACKWARDS. :smile :

The alternator and V belt and water pump">raw water pump are AFT instead of at the "front" of the engine.

While the boat is well thought out and there's "good" access at the aft end of the engine, which to most of us would be the front on the engine, it is necessary, IIRC, to get to it through the aft cabin or a long reach from the galley where the engine cover lifts up.

It "could" be a maintenance issue.

As long as the builder had actually "designed" in engine access, it's something to be aware of when looking.

The e33 is a very nice example of how to do it right.

I still like my shaft --- the one on the boat.
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Old 09-02-2016, 16:13   #11
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Re: Saildrive VS Direct Shaft

Quote:
Originally Posted by stefano_ita View Post
Thanks...

About engine placement what is the difference?

I saw boat of same dimension, same layout, some with saildrive and some with direct shaft (long about 6-7+ feet) with the aft part going up quite vertical, some with much inclined prop shaft but shorter...

For cost and time installation in a supply chain for sure saildrive win, until the owner get his new boat...
With a saildrive, the prop is almost directly under the engine. With a shaft drive, it needs to be behind the engine - and if the engine is higher than the propellor, the further away it is, the better it is for the angle of the drive shaft. You really want your prop to be pushiing as close to horizontally as possible

In the case of my boat, saildrives mean that the engines can be in separate compartments in the sugar scoops behind the accomodation. If they were shaft drives, the engines would have to be further forward under the rear bunks - using up valuable storage space, increasing noise, heat vibration in the accommodation and making them harder to access and work one.

Plus I have a bulkhead between the engine compartments and the main hulls meaning that in the even of a catastrophe, flooding is limited to that compartment.
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Old 09-02-2016, 16:19   #12
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Re: Saildrive VS Direct Shaft

Quote:
Originally Posted by Pete7 View Post
I believe at one of the boatshows Volvo had a fish tank with the seal in it. They had a divers knife through the seal.

My propellor on a shaft is about 15" from the rudder so in close quarters water is directed straight over the rudder giving instant turning forces. Have a think about a sail drive with the prop 2/3rds along the hull.


Pete
You are right, i forgot this
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Old 09-02-2016, 16:23   #13
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Re: Saildrive VS Direct Shaft

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Originally Posted by rabbi View Post
Most of them are boat builders.


all things being equal - and if I had the choice- I'd prefer straight shaft.
Not many small cats around with that, so its more a theoretical question.

I remember a Lagoon 500 (called nipper?) sank because the dinghy painter got into the prop which dislocated the saildrive.
We had a similar incident in our previous boat: Ran into a pile of fishing net, cracked the saildrive bed and had some minor leak which required a haulout a few days later.

But: we now have saildrives, too.
Interesting too...

Do you had mechanical or hydraulic gearbox? It must have lot of turque and do not slip the clucht to almost districate the saildrive...

Does it just moved from the bolts or the bolts cracked the fiberglass around them?
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Old 09-02-2016, 16:25   #14
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Re: Saildrive VS Direct Shaft

Quote:
Originally Posted by Stu Jackson View Post
A good friend has a Hunter e33 with the saildrive. Engine placement? His engine, to me, is in the boat BACKWARDS. :smile :

The alternator and V belt and raw water pump are AFT instead of at the "front" of the engine.

While the boat is well thought out and there's "good" access at the aft end of the engine, which to most of us would be the front on the engine, it is necessary, IIRC, to get to it through the aft cabin or a long reach from the galley where the engine cover lifts up.

It "could" be a maintenance issue.

As long as the builder had actually "designed" in engine access, it's something to be aware of when looking.

The e33 is a very nice example of how to do it right.

I still like my shaft --- the one on the boat.
Thanks,

The photos has been taken by opening an acced from the aft cabin alright? for extra mainteniance do you hang up the compantionway's ladder?
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Old 09-02-2016, 16:25   #15
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Re: Saildrive VS Direct Shaft

Quote:
Originally Posted by Pete7 View Post
I believe at one of the boatshows Volvo had a fish tank with the seal in it. They had a divers knife through the seal.

My propellor on a shaft is about 15" from the rudder so in close quarters water is directed straight over the rudder giving instant turning forces. Have a think about a sail drive with the prop 2/3rds along the hull.


Pete
My saildrive propellors are so close to the rudders that I can't fit folding props
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