SailDrive or Shaft

[fastcat435]

Originally Posted by Gludy

I would be all for IPS units in cats - in many a marina/docking situation in wind it could prove very helpful.

Sounds like a great idea and if you mount the new IPS 850 you can get 30 knots out of your new St Francis lollollol

Gideon

[rtbates]

Originally Posted by jzk

This would be too complicated to be of any value on a sailboat. Your sailboat already has rudders for steering under sail. What is the point of the IPS?

For powerboats, IPS is probably the single best innovation ever. A 10 year old can now dock a 50 footer with ease. I drove a 50ft Regal with IPS, and it is simply amazing.

Thrust vectoring? So a 10 year old could dock your 75 footer in a 20 kt crosswind?

[Whimsical]

Originally Posted by rtbates

Thrust vectoring? So a 10 year old could dock your 75 footer in a 20 kt crosswind?

Yep
Throttles and rotation are electronic and interfaced to the gps and heading sensors etc and it will compensate for gusts, currents etc. It has a small knob on top of the joy stick that when twisted rotates the boat. Moving the joystick moves the boat in the required direction.
Would be realy serious fun

Mike

[fastcat435]

We use the system in our Powercat 420 and are extremely happy with the system.
Getting into a dock can be done by anybody that can ride a bicycle, it is like point and shoot

Greetings

[Adaero]

Originally Posted by Gludy

Gideon - you say you have to lift the boat out to change oil but another post says that this is not the case with the new saildrives ..... which is right?

Paul

I will have the 54hp Yanmar 4JH4E and SD50 sail drives on the Leopard. You can change the oil on both the engine and drive using one of these: -
PELA 6000 / SEAGO OIL EXTRACTOR | Marine Super Store
They are £30 from most swindleries. You push the pipe down the dipstick hole to the bottom of the sump, pump the handle 5 times and it then sucks the oil out. The bowl is graduated so you can make sure you have all of the oil from the system.
The comment about having to remove the prop to change the zincs is correct as they are ring shape which is a pain. You can still change them in the water with a small air tank and mask, not a difficult job really.

[jzk]

Originally Posted by rtbates

Thrust vectoring? So a 10 year old could dock your 75 footer in a 20 kt crosswind?

Yes. That is exactly right. It is a joystick. The GPS interface is not functional yet, nor is there any compensation for currents and wind. But that becomes pretty natural with the joystick. And the IPS has several speeds, so I think a 20 knot wind would be doable.

[schoonerdog]

With yanmar saildrives, depending on the prop, you can use a two part collar type zinc which makes it far easier as you don't have to remove the prop first. My boat has two different props, one you can use a two part collared zinc and one you can't. With folding props though taking them off underwater becomes exponentially harder. I'd would choose straight shafts anyday, far less maintanence and less worry. The through hull intakes from saildrives also seem pretty prone to getting frozen open. My bronze folding props show signs of electrolysis which couldn't have been helped being at the end of an aluminum drive leg. It seems when saildrives hit around 10-15 years they often need to be replaced. Your mileage may vary.

[beiland]

Naturally straight shaft drives are the simplest, most proven, and reliable systems out there. But the do restrict the engine placements in the vessel, and most often are tied to the engine in a such a manner that the engine can not be truly vibration-free mounted.

Outdrives begin to look good, but there are problems with them:
From my website,"Other than direct straight-shaft drive of propellers, most marine drives today involve some sort of 90 degree arrangement, ie.sail drives, stern outdrives, outboards, etc. The 90 degree gear set (and there are usually two sets) is the potential weak link in the system. All the power is being transferred over a very physical small contact area between two bevel gears. This contact patch can be nothing more than a thin line on the opposing two teeth!
I had previously suggested this idea for both single and/or dual props, but utilizing a Kevlar belt drive component rather than 90 degree shafts

Here are a few references to different idea on a propulsion unit. I may try to have some of these built over in Thailand after I move there.

Chain or Belt Drive Prop Unit

Boat Design Forums - View Single Post - Future Sportfisherman Looks like the Past?

[BigCat]

If you have room for a shaft drive, go with that. I have read many a post and blog describing problems with saildrives, all of which have been mentioned in this thread. To eliminate vibration, go with an Aquadrive system. Aquadrive The fellow who bought my old boat put in a bigger engine, and installed an Aquadrive system. I couldn't tell when the engine was running, even though all that was between me and it was a piece of plywood. From a design standpoint, the benefit / drawback of a saildrive is that the engines are mounted further aft. This gives more interior room for the accommodation but has the potential of exacerbating pitching, and depressing the stern. If you plan on doing a lot of motoring, I wouldn't use a super lightweight engine like a Yanmar. I'd go with a 4 cylinder Deere.