Advantage of the newer cutlass styles

[dakardad]

Originally Posted by SV Maclas

We have a composite cutless on our aluminum boat for the obvious reason of reducing corrosion. Sure is easy to get out!

A composite tube or actual bearing?
How is your shaft wearing?

[Irish rambler]

Sorry to butt in to the discussion. the obvious place to start is at the engine, a 5 or 6 cylinder engine will be smoother and quieter(less vibration). New common rail diesels are indeed very smooth and economical with bags of torque. I don't like electronics in the engine room (warm damp salty air), I like to be able to fix a problem myself if one occurs offshore and for that reason I would go for a Merc 5 or 6 cyl or Toyota 6cyl both are very easy to marinise and parts are available worldwide. If the engine is mounted on soft mounts and a thrust bearing fitted to the prop shaft you can virtually eliminate the vibration. A bronze cutlass bearing with a PSS shaft seal will give you an enviable set up that will give you years of trouble free cruising.
Worth thinking about if you're refurbing your boat.
I agree the VW 6 is butter smooth but don't forget it has a timing belt which must be changed when due without fail. The other engines I mentioned have chain driven overhead cams.

[dakardad]

Thanks for the replys. The prop apperture size wont
Allow for a rubber style cutlass brng. So I needed
An alternative. My question had nothing to do
With eng choice, thats decided.
Ive decided to go with a bronze or SS tube with replacable bushings.
I like the thought of a grease filled tube that
I can give a squirt of grease to now and again.
ANY single cyl is gonna shake a bit, hydraulic drive
is being mulled over, not sure yet.

[alexandlorna]

Surely the losses in a hydraulic drive would be far to great for a single cyl engine .

Alex

[dakardad]

Originally Posted by alexandlorna

Surely the losses in a hydraulic drive would be far to great for a single cyl engine .

Alex

No not really. A well designed hyd drive is about
95% efficient. Number of cyl doesnt matter.
The great advantages are flexibility with
Engine placement , vibration isolation
And thrust control.
If l go this way l plan on putting my engine
on casters so l can slide it out from its 'hole'.
Downsides are potential leaks.

[Adelie]

Bronze bushing would have wear and overheating problems.

[NahanniV]

Originally Posted by Adelie

Bronze bushing would have wear and overheating problems.

Bronze bushing would need grease (as mentioned earlier).

No reason for it to overheat, impossible if submerged.

[NahanniV]

Originally Posted by dakardad

No not really. A well designed hyd drive is about
95% efficient. Number of cyl doesnt matter.
The great advantages are flexibility with
Engine placement , vibration isolation
And thrust control.
If l go this way l plan on putting my engine
on casters so l can slide it out from its 'hole'.
Downsides are potential leaks.

A neighbor of mine had a single cylinder Farryman diesel with hydraulic drive.

It worked well on his 33' boat, but a big problem was noise from the hydraulics.

[dakardad]

Originally Posted by Adelie

Bronze bushing would have wear and overheating problems.

If given proper clearances and
proper meterials, no, it will not overheat.
Before rubber, there was bronze.

[dakardad]

Originally Posted by NahanniV

A neighbor of mine had a single cylinder Farryman diesel with hydraulic drive.

It worked well on his 33' boat, but a big problem was noise from the hydraulics.

Yes, that can be a problem.
It can be controlled by the types of pump and motor
And valving Combinations. The pump, since its always pumping when
The engine is running, maintains a high line pressure, pump
Back up, and noise. Its the set up that makes
It or breaks it on noise.

Thanks for chiming in. Given the constant consternation
About no work space around the engine, l dont see why
More people dont use it.

Hyd drive is so easy and simple to maintain too.
Pumps and motors are a breeze to rebuild.

[MarkSF]

Originally Posted by Irish rambler

Sorry to butt in to the discussion. the obvious place to start is at the engine, a 5 or 6 cylinder engine will be smoother and quieter(less vibration). New common rail diesels are indeed very smooth and economical with bags of torque. I don't like electronics in the engine room (warm damp salty air), I like to be able to fix a problem myself if one occurs offshore and for that reason I would go for a Merc 5 or 6 cyl or Toyota 6cyl both are very easy to marinise and parts are available worldwide. If the engine is mounted on soft mounts and a thrust bearing fitted to the prop shaft you can virtually eliminate the vibration. A bronze cutlass bearing with a PSS shaft seal will give you an enviable set up that will give you years of trouble free cruising.
Worth thinking about if you're refurbing your boat.
I agree the VW 6 is butter smooth but don't forget it has a timing belt which must be changed when due without fail. The other engines I mentioned have chain driven overhead cams.

Even a 3 cylinder diesel can be made very smooth with use of balance shafts. Unfortunately most of our diesels were intended to be used in tractors, where adding a lot of cost and complexity to make it smoother doesn't make much sense.

I'd certainly pay to make my 3 cylinder Kubota smoother.... 3 cylinders have a nasty fore-aft rocking moment which needs a balance shaft to remove.

I have a Passat TDI at home, which is turbine smooth... I looked it up and they have twin balance shafts now, on the 4 cylinder.

[alexandlorna]

I would not argue re the simplicity, smoothness and convenience of hydraulic drives , however many river boats here have them and they do not have a wonderful reputation .
Certain pump valve combos will allow for unloading at idle and keep the heat generated down to a minimum , but these pumps are very expensive and not at all easy to maintain or rebuild .
If simple gear type pumps are used the result will be heat ,noise and leaks
The idea of castors seems novel - I assume you intend to provide means to isolate the castors from the system when in running configuration ?

Alex

[S/V Alchemy]

I have a Thorden Elastomeric stern tube bearing, an Aquadrive and soft engine mounts. Don't reinvent the wheel: unless you are doing some sort of museum job, there are far better modern materials that can work in wood, but you have to ask the fan of wooden boat building who isn't quite so sentimental as to go all wood.

I recall a wooden boat builder saying that the wooden warships until 1860 or so weren't popular...they were the best choice of a bad lot of potential shipbuilding materials. As soon as the industrial processes were available to make sheet iron, reliable rivets and iron frames, navies both military and merchant went to them as soon as it was practical to do so.

I like wooden boats, but I wouldn't hesitate were I to build one to use the most modern and efficacious of sealants, bearings and assorted moving parts. Wood and ocean are antagonistic, after all.

[siboneysail]

A stainless steel tube will most likely suffer crevice corrosion on the outside of the tube. Go with fiberglass.