Reply
 
Thread Tools Search this Thread Display Modes
 
Old 06-16-2021, 07:30 PM   #1
Guru
 
Benthic2's Avatar
 
City: Boston Area
Join Date: Feb 2017
Posts: 1,912
Why aren't sail drives more common ?

I just learned about sail drives today and they seem like a great idea ? You can move the engine(s) to the stern for noise and space reasons, you don't have the inneficiency of a propeller angled downward and you avoid drive shaft/cutlass bearing/stuffing box issues.

So...I have to believe that if they really were better they would be more common. I am always curious when there is one technology that doesn't dominate or die, kind of like Mazda's rotary engine.

So, why aren't they more common ?

( thanks in advance )
Benthic2 is online now   Reply With Quote
Old 06-16-2021, 07:36 PM   #2
TF Site Team
 
Comodave's Avatar
 
City: Au Gres, MI
Vessel Name: Black Dog
Vessel Model: Formula 41PC
Join Date: Jul 2015
Posts: 12,196
Have you seen the Volvo IPS? Pretty much like a saildrive but more powerful and way more expensive. And they are Volvos…. Parts are expensive if you can get them. The drives have to be resealed periodically or else.
__________________
Boat Nut:
If you are one there is no explanation necessary.
If you aren’t one, there is no explanation possible.
Comodave is offline   Reply With Quote
Old 06-16-2021, 07:53 PM   #3
Guru
 
psneeld's Avatar
 
City: Ft Pierce
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 23,994
corrosion.... by now though.... if made from composite housings a lot of issues could be eliminated.


and hard to check for water intrusion into the lower gear area.
psneeld is offline   Reply With Quote
Old 06-16-2021, 08:12 PM   #4
Art
Guru
 
Art's Avatar
 
City: SF Bay Area
Vessel Model: Tollycraft 34' Tri Cabin
Join Date: Feb 2011
Posts: 11,228
Saildrives

https://www.boats.com/reviews/all-about-saildrives/
Art is offline   Reply With Quote
Old 06-16-2021, 08:12 PM   #5
Guru
 
BruceK's Avatar
 
City: Sydney
Vessel Name: Sojourn
Vessel Model: Integrity 386
Join Date: Oct 2011
Posts: 11,488
Sail Drives suffer from the same issues as outdrives/sterndrives. It`s keeping water out and oil in, and why locate the gearbox under water.
__________________
BruceK
2005 Integrity 386 "Sojourn"
Sydney Australia
BruceK is offline   Reply With Quote
Old 06-16-2021, 08:17 PM   #6
TF Site Team
 
Comodave's Avatar
 
City: Au Gres, MI
Vessel Name: Black Dog
Vessel Model: Formula 41PC
Join Date: Jul 2015
Posts: 12,196
Quote:
Originally Posted by BruceK View Post
Sail Drives suffer from the same issues as outdrives/sterndrives. It`s keeping water out and oil in, and why locate the gearbox under water.

Particularly salt water.
__________________
Boat Nut:
If you are one there is no explanation necessary.
If you aren’t one, there is no explanation possible.
Comodave is offline   Reply With Quote
Old 06-16-2021, 09:38 PM   #7
Guru
 
tiltrider1's Avatar
 
City: Seattle
Vessel Name: AZZURRA
Vessel Model: Ocean Alexander 54
Join Date: Aug 2017
Posts: 2,634
A sail drive is superior in all aspects except simplicity. Here is were it all comes a part. The complexity suffers more maintenance in wear and corrosion which means more cost and more break downs. Add to this that sail drive manufactures were quick to abandon their product in the past, leaving boat owners with a hole in their boat not easily filled. Quickly the end user learned to avoid all these issues and sail drives ended with a bad reputation that was well deserved.

Here we are again with the old timers wondering if history is about to repeat itself.
tiltrider1 is offline   Reply With Quote
Old 06-16-2021, 10:12 PM   #8
Guru
 
Benthic2's Avatar
 
City: Boston Area
Join Date: Feb 2017
Posts: 1,912
My introduction to sail drives was when I was reading about the Marlow Mainship 32 and thought that the 6 miles per gallon at 9 mph was impressive. The Boattest.com article pointed out that pods can be 30-50% more efficient than shaft drives but admitted that some of that is due to reduced drag from the absence of rudders.
Benthic2 is online now   Reply With Quote
Old 06-17-2021, 12:11 AM   #9
Art
Guru
 
Art's Avatar
 
City: SF Bay Area
Vessel Model: Tollycraft 34' Tri Cabin
Join Date: Feb 2011
Posts: 11,228
IMHO

In Saltwater: Out drives, saledrives, pods - are similar to Alka-Seltzer in water... they fizzle too easily!

Not to mention too many other product complications.
Art is offline   Reply With Quote
Old 06-17-2021, 05:33 AM   #10
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 21,964
For a novice , sail drives can make the boat self docking , but at huge cost.
FF is offline   Reply With Quote
Old 06-17-2021, 07:44 AM   #11
Guru
 
City: Rochester, NY
Vessel Name: Hour Glass
Vessel Model: Chris Craft Catalina 381
Join Date: Aug 2019
Posts: 3,660
Sail drives, pods, stern drives all have some efficiency advantage (particularly if the rudders are eliminated), but it's not worth the maintenance headaches in my mind. And low speed steering is usually not as good with no rudders, as you're only steering with thrust (and you lose that as soon as you take the engines out of gear).
rslifkin is offline   Reply With Quote
Old 06-17-2021, 07:49 AM   #12
Guru
 
City: Owings, Md
Vessel Name: Graceland
Vessel Model: Mainship 34 MK1
Join Date: Jan 2016
Posts: 575
Talk to some sail drive owners that wet slip their boats and ask their opinions. They are not very robust and you have no way to check for water containination without pulling the boat. They are well suited to boats kept on a lift. IPS drives look like a risky proposition to me best suited to folks with deep pockets that can replace them without thinking twice of the cost. The fuel savings realized over several seasons could be wiped out with one log and who knows what the availability of those drives will be in 10 years. Outdrives can be pricey enough to replace and they are much more common, I would hate to spend $1-2M on a boat only to lose a drive and find it is no longer made and now I need to retrofit the whole system to get operational again. Doesn't seem worth it for a trawler style use.
Gdavid is online now   Reply With Quote
Old 06-17-2021, 07:54 AM   #13
Guru
 
psneeld's Avatar
 
City: Ft Pierce
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 23,994
Completely disagree that directed thrust boats (I/Os and outboards) are less maneuverable....with the exception maybe some/many jet drives and that depends dramatically on hill shape


If talking singles, I find driving I/Os by far the most maneuverable, outboards a little less so because they physically don't turn as far and smaller profile in the water. A good sized I/O is much like a rudder even out of gear...but you don't need to use it like that once you get the hang of them.


Many single I/O's properly driven can do a 180 in almost a boat length... much like pivoting with twins. Try that with a single conventional shaft/prop and no thruster.



Twins are of course a different animal and can vary between setups.
psneeld is offline   Reply With Quote
Old 06-17-2021, 08:00 AM   #14
Guru
 
City: Rochester, NY
Vessel Name: Hour Glass
Vessel Model: Chris Craft Catalina 381
Join Date: Aug 2019
Posts: 3,660
Quote:
Originally Posted by psneeld View Post
Completely disagree that directed thrust boats (I/Os and outboards) are less maneuverable....with the exception maybe some/many jet drives and that depends dramatically on hill shape


I find driving I/Os by far the most maneuverable, outboards a little less so because they physically don't turn as far and smaller profile in the water. A good sized I/O is much like a rudder even out of gear...but you don't need to use it like that once you get the hang of them.


Many single I/O's properly driven can do a 180 in almost a boat length... much like pivoting with twins. Try that with a single conventional shaft/prop and no thruster.



Twins are of course a different animal and can vary between setups.

They're maneuverable, but when I say they don't handle well, I'm referring to tracking, steering authority, etc. when just cruising at low speeds. A lot of sterndrive boats tend to wander at low speeds, for example.
rslifkin is offline   Reply With Quote
Old 06-17-2021, 08:01 AM   #15
Senior Member
 
City: Grand Rapids, MI
Vessel Name: Arcturus
Vessel Model: 1973 Concorde 41 DC
Join Date: Sep 2020
Posts: 187
You see quite a few of them on sail boats, but their only advantage is installation cost. Probably a quarter the labor of a traditional shaft. So cheaper sale price and/or higher profits for the builder. Higher maintenance costs but the builder doesn't care about that, not his problem. True there's no shaft alignment to worry about but having to periodically replace the rubber seal greatly out weighs that and it's a haul out job.
jgwinks is offline   Reply With Quote
Old 06-17-2021, 08:07 AM   #16
Guru
 
City: Owings, Md
Vessel Name: Graceland
Vessel Model: Mainship 34 MK1
Join Date: Jan 2016
Posts: 575
Quote:
Originally Posted by rslifkin View Post
A lot of sterndrive boats tend to wander at low speeds, for example.
I have a little bowrider with a stern drive that wanders so bad that I'm afraid of being pulled over in the harbor under suspicion of being under the influence. It is really beamy and shallow draft and I believe it is caused by vortexes being shed off of the transom corners at a frequency. It will drive you crazy.
Gdavid is online now   Reply With Quote
Old 06-17-2021, 08:11 AM   #17
Guru
 
City: Rochester, NY
Vessel Name: Hour Glass
Vessel Model: Chris Craft Catalina 381
Join Date: Aug 2019
Posts: 3,660
Quote:
Originally Posted by Gdavid View Post
I have a little bowrider with a stern drive that wanders so bad that I'm afraid of being pulled over in the harbor under suspicion of being under the influence. It is really beamy and shallow draft and I believe it is caused by vortexes being shed off of the transom corners at a frequency. It will drive you crazy.

Yup, that's exactly what I'm thinking of. Some say dropping the trim tabs all the way stabilizes things a bit, but so does having rudders.
rslifkin is offline   Reply With Quote
Old 06-17-2021, 08:14 AM   #18
Guru
 
diver dave's Avatar
 
City: Palm Coast, FL
Join Date: Jan 2017
Posts: 2,052
Quote:
Originally Posted by Benthic2 View Post
I just learned about sail drives today and they seem like a great idea ? You can move the engine(s) to the stern for noise and space reasons, you don't have the inneficiency of a propeller angled downward and you avoid drive shaft/cutlass bearing/stuffing box issues.

So...I have to believe that if they really were better they would be more common. I am always curious when there is one technology that doesn't dominate or die, kind of like Mazda's rotary engine.

So, why aren't they more common ?

( thanks in advance )
They are very common with sail cats. I would say the majority of volume of production sailcats use either the volvo or the yanmar saildrives. Mostly driven by increase efficiency of space, ease of production/installation, and elimination of the stuffing box failure point.
Another advantage is elimination of rear stateroom heating, after a run.
I'm getting 5.5nm/gal in my boat @ 6.x knots, no sails up.
diver dave is offline   Reply With Quote
Old 06-17-2021, 08:15 AM   #19
Art
Guru
 
Art's Avatar
 
City: SF Bay Area
Vessel Model: Tollycraft 34' Tri Cabin
Join Date: Feb 2011
Posts: 11,228
Soooo... by reading posts here and from my years [decades] of experience - IMO:

Widely spaced twin engines' straight shaft-to-prop drives, with twin rudders of ample size, win the contest for general boat maneuverability during the full range of [slow or fast] speed conditions. Add bow and/or stern thrusters [both of which I feel unnecessary on a twin engine boat]... then the water-floating boat becomes similar in [level-plane maneuverability] to an air-floating "helicopter".

What's not to love - Twin Screws for Me!!
Art is offline   Reply With Quote
Old 06-17-2021, 08:17 AM   #20
Guru
 
psneeld's Avatar
 
City: Ft Pierce
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 23,994
Many smaller vessels with outdrives do suffer from tracking ability...that's because they are designed for watersports not really "cruising". Bowriders are often way too bow heavy due to loading and thus wander at low speeds quite a bit. Put everyone aft and it improves on many bowriders.

Loading of these vessels is often critical for the wandering issue and also is trimming to eliminate porpoising and chine walking at higher speeds.

Jet drives with mostly flat bottoms are really a handful to handle till you learn their habits....but they are designed for purposes that really aren't slow speed tracking or long distance cruising.

Outdrives in large vessels dont have these issues as the hulls are more "cruiseworthy" designs, not sportsters.

Once above 30 to 35 feet and heavier type hulls (no go fasts)....are there that many I/Os? I haven't been looking closely. In fact, I think Sea Ray all but eliminated I/Os and went outboards in their smaller boats. At least they started to when I worked for a dealership back in the early 2000s.
psneeld is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Trawler Port Captains
Port Captains are TF volunteers who can serve as local guides or assist with local arrangements and information. Search below to locate Port Captains near your destination. To learn more about this program read here: TF Port Captain Program





All times are GMT -5. The time now is 05:13 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012