Converting from shaft drive to sail drive - Questions

[Souzag818]

RaymondR
The fact that he hit something with "one" of his saildrives leads me to think it was a cat, which wouldn't roll. More of a problem with the boat type, than the means of propulsion. Probably would have cause damage if he had shaft drives too. My saildrive is behind my keel, in front of my skeg hung rudder.. I'm convinced it would have rolled too.



I'm not trying to make this a debate about saildrives. I'm just sharing my personal experiences with them, not some second hand experience. As I said before, I wouldn't not buy a boat because it had a saildrive. They don't scare me. Synthetic rigging....that scares me....

[hlev00]

Bill Whitmore - can you elaborate with some more examples and what kind of boat you have? It sounds like you have valuable information to share.

[Toccata]

A few observations that may help make your decision.
I had a V Drive on a displacement power boat.
V Drive was Noisy, another oil to change/monitor. I could not see the shaft seal, it too was under the engine. The alignment of the shaft to the V Drive/gearbox was challenging due to the mount design (of the Twin Disc V Drive). All reasons to move away from it. A local Naval Architect offered the thought that the V Drive "is a solution to a design problem that possibly shouldn't have been designed into the boat in the first place"
My experience is with a Yanmar SD60 in a 46' monohull with a conventional keel. The sail drive is close to the aft edge of the keel (400mm space) I have just fitted a Flex O Fold prop. Excellent drive in both Fwd and Rev. Some prop walk. Oil change can be done via the dip stick(while in the water). The ring style anode is fiddly to change. The hub seals (O Rings) in the prop shaft hub, are easy to change. Operation is Very Smooth, vibration free. The hull seal/boot is very substantial. The engine sits level in the boat. There is space aft of the engine in the bilge area (usually occupied by the shaft/log.
I have seen a boat accidentally lifted by a sling caught under the sail drive, the rubber boot survived that force/movement!
The rubber guard on the external surface of the hull, is a bit "ordinary" doesn't hold antifoul very well and is a replacement/maintenance item.
I'm not anxious about it as a weak point of the boat, but it is another area to keep a watchful eye on.
At this stage I wouldn't not buy a boat with a sail drive, but I acknowledge that the drive is going to be more maintenance than a conventional shat drive. I certainly wouldn't choose a boat with a V Drive again.

[Sand crab]

Some have had success with removing the saildrive oil (on some) without hauling out the boat. It's here on the forum.

[Captain Bill]

First of all, any saildrive compatible with his engine will have the ability to have its gear oil changed in the water. T


The great fear of weakness in the saildrive installation is also so much BS. A couple of weeks ago we had an unusually low tide event and I hit a "known rock" in the main canal that leads to my canal but is not marked. I had been told where it was and thought I was far enough over to miss it, but I wasn't. The keels on my endeavour cat slope upwards towards the bow. When I hit the rock the port hull lifted a good 6 to 8 inches before falling off the rear of the keel and dropping the saildrive directly on the rock. Nothing at all came loose, leaked, cracked, ripped out, flooded the boat, or anything else lurking in the minds of people who live in fear of saildrives. Yea, the paint on the bottom of the drive is scraped and I bent a blade of my feathering prop 45 degrees (that's the big ouch). I also once picked up a string of 10 lobster pots in Maine while ailing at 8 knots with the current with me and it drug my 44 foot cat to a dead stop in about a boat length or two. Again no damage at all. I on the other hand had a shaft drive shear a coupling, yank the shaft back and jam the rudder with the prop, all while letting a significant amount of water into the boat through the now compromised shaft seal. All this from a single small crab pot. This fear of saildrives is pretty much based on a very active imagination.

[MJH]

Originally Posted by chowdan

Hey all,

I am not looking to do this right now - I just wanted a video of a popular youtube channel where they converted from shaft to saildrive in an effect to get their electric system more efficient and this got me thinking.

As some of you know I am a full time live aboard, working on rebuilding/setting up for cruising while saving up and awaiting for my now hopeful stock option pay out in 2 years before I head out cruising. Goal is to cruise from PNW down the coast to Baja, do a bit of cruising in Sea of Cortez then make the jump over to the south pacific and from there who knows.

That being said, our boat is a fairly heavy boat - 42ft and last haul out prior to moving aboard and being loaded was weighing in @ 36,000 lbs. In reverse she has really terrible prop walk to starboard - we have to goose it out of the slip for the first 30 feet or so before the rudder kicks in.

The other thing is that our engine is using a V drive transmission. The shaft comes in through the boat right under the engine and as such, visually we can not see our shaft or shaft seal - major concern of mine since you can't monitor its state.

That being said, after watching their conversion video I started thinking about it. THe biggest pro for me IMO would be the fact that the engine can be rotated to face forward and that the shaft doesn't live under the engine where i can't inspect it.

Does anyone have any opinions on this conversion? Has anyone personally done it? What was the experience like?

PROS:
- Engine can face forward - no longer have to climb through small access holes to just work on something like the alternator
- No longer have the worry about alignment issues
- Shaft seal is removed(though replaced with something else)
- Sail drive is inspectable
- Future wise can upgrade to all electric and gain regen
- Engine MAY be able to move aft - giving more working room
- Prop walk reduced or gone

CONS:
- PITA to service in far away locations
- Requires haulout for oil changes
- Stray current causes corrosion
- Obviously things I am not thinking of

PS my engine is a Yanmar 4JH2-UTE - 100hp turbo.

With that weight I'm guessing your boat has a full keel...how does that mesh with a proposed sail drive?

Most V-Drives I've seen were done to enhance the salon layout. Have you thought about replacing the V-Drive with a straight shaft and then redesign the salon instead?

I once thought of replacing a straight shafted Tayana 37 with a sail drive but then got my head on straight and didn't buy the boat.

With all the above said, I think such a replacement is more than I would want to undertake. Despite my dislike of V-Drives there have been successful circumnavigations with them i.e. Valiant 40s.

Good Luck.

~ ~ _/) ~ ~ MJH

[RaymondR]

Originally Posted by Souzag818

Don't see how he split a rubber boot without causing serious damage to his engine or saildrive. Both parts are bolted together and don't move independently. And it is rubber...

It surprised me that the engine/drive unit could move sufficiently to split the boot without damaging the engine mounts but it did. I suspect that the elastomer in the boot hardens with time.

[Pete7]

Originally Posted by chowdan

That being said, our boat is a fairly heavy boat - 42ft and last haul out prior to moving aboard and being loaded was weighing in @ 36,000 lbs. In reverse she has really terrible prop walk to starboard - we have to goose it out of the slip for the first 30 feet or so before the rudder kicks in.

We have the same prop walk to starboard and actually once used to it can be very useful to get out of a berth in reverse or off a pontoon. Some props are worse than others, there is a review of folding props in the CF library which you might want to review.

I think if I was going to put a sail drive in, then like Uma how about an electric drive and a generator? won't be cheap, but means the genny can go nearby but doesn't need to line up. Electric drive doesn't have the cones and gears either I think.

The one other solution is a bow thruster, but these are all big expensive jobs and its easy spending someone else's money. Sometimes I am really grateful we only have 31ft and can just push to the boat out with a gentle shove or turn it around with a couple of pieces of old rope.

Pete

[olaf hart]

I recall seeing a Pearson 424 that had its V drive engine replaced with a saildrive and forward engine, the pod was further aft than the prop shaft so you probably have to check how much room you have before your rudder or skeg.

The boat worked well, much better access.

I currently have a Valiant 40 with a V drive 4jh yanmar, it behaves well but has the same issues you are complaining about, I can’t even see my stern gland..

Tempted to go with a saildrive if I ever re engine, hope it never happens...

[carlosproa]

There are 2 YouTube videos from the channel “Sailing UMA”. You may want to check it out. As they went from shaft to sail drive and DIY

[Brewgyver]

Originally Posted by carlosproa

There are 2 YouTube videos from the channel “Sailing UMA”. You may want to check it out. As they went from shaft to sail drive and DIY

Why can't people try reading AT LEAST the first post of a thread before replying?

The OP already watched them, and said so in the first paragraph of this post (though he did type "wanted" when he obviously meant "watched"). He said those videos "got him thinking."

This is the second time in this thread somebody replied saying "you should check out Uma"

[RaymondR]

It seems an awful lot of trouble and expense for limited returns. You have to remove the entire existing arrangement, then patch a big hole in the bottom of your boat, then install the V drive. Not a trivial exercise and you are exchanging an existing arrangements with a couple of relatively minor inconveniences for one with it's own set of inconveniences.

I'd be inclined to spend a little time attempting to solve the problems with the present arrangement before embarking on what appears to be a major modification to the boat.

[nortonscove]

The Youtubers "Sailing Ima" just did this but with an electric refit. They did what looked like a great job.

[Brewgyver]

Originally Posted by nortonscove

The Youtubers "Sailing Ima" just did this but with an electric refit. They did what looked like a great job.

Really??? You don't say!

[sailingchiro]

I absolutely enjoy how simple the shaft drive is. In your case though, you can't see what is under your engine.
I would be more interested developing easier ways to inspect under your engine rather than reinventing the wheel while throwing alot of money and time at the problem. Not to mention making it more complicated.

Do what all warm blooded men do, buy more tools.

Specifically, an inspection camera that can do a close up under your engine. I have one and can't believe how many times I reach for it (lost tools, lost fasteners, fuel tank growth, looking behind refrigerators, looking for leaks on the bottom of machinery, etc.). You can actually record it for later use.
I have often thought about setting up camera's in my engine compartment and bilge in order to monitor on passages.

On a side note, I have an infrared thermometer and use it to take temps off different parts of my engine, transmission, shaft seal and bearings, water pump, water jacket, etc. under normal use. I know the normal temps of all those items and inspect them often on long passages and during normal use. These temps go in the engine logs.