Evolution Marine Shaft System

Does any one here have expereince with, The Evolution Marine Shaft System? It looks to me that it solves a number of shaft and stern tube problems, however, I know nothing is perfect.

 

Im not familiar with the company Evolution or its shaft logs but Ive been using oil bath, thrust bearing shaft logs for 30 years. Very reliable, they eliminate exposed SS underwater ,reduce rotational friction and remove shaft thrust off the engine mounts so less noise is transmitted into the hull. . Because of the low friction The system is particularly well suited to sailing yachts who free wheel the propshaft to generate electricity or hydraulic power for autopilots. Good stuff.

A common problem with oil seal shafts is Monofilament fishing line getting between the prop hub and the oil seal and damaging the seal. Ask Evolution what design detail they use to protect the exterior oil seal.

The pictured oil bath shaft log is by Federal and has about 13,000 rotational hrs and no problems.

 

Thanks for the reply. Evolution also has line cutters that they reccomend to keep that pesky mono at bay. I would think that the oil bath system would be more reliable then the more traditional system, however, I'm sure it more expensive.

 

Its the best !!! No comparison with a cutless, stuffing box setup.

Oil bath shaft logs are expensive. Important that Evolution supervise the commissioning of the shaft log or provide good technical notes. When setup correctly the system is maintence free.

Does Evolution use oil ? Or some other fluid for lubrication. Ive been told that because of new pollution regulations the design of modern shaft logs is different ?

By the way oil, lubrication , of the shaft log is supplied by an oil header tank located well above waterline. . This header tank supplies gravity fed positive oil pressure to the assembly.

The line cutter may or may not work with fine monofilament fishing line. I pick the stuff up mostly when retrieving the anchor. The bottom of some harbours is full of the stuff. Its very fine. The defense against it is very close tolerance fit between the prop hub and the shaft seal and inspecting for monofiliments buildup in this joint at each haulout .

The seal on this Federal log is spring pressure loaded to maintain contact with the prop hub and keep line from building up. . I didn't see a drawing of the Evolution log....I guess the details are intellectual property. Good to inquire about how this outside seal works. The inside seal is a common lip seal...

If I can find a drawing I will post

 

On ships there is an IMO spec for shaft oil as its is biodegradable hence legal to enter the water.

Hi Micheal
I dont neccessaily see how an oil bath removes the thrust from the engine, there are plenty that dont.

 

It is a good company - I have a friend that has positive experience with them. One funny thing, one of their testimonials: "On Parisen's boat (38' Duffy with a 420-h.p. Lugger diesel), the individual who was going to 'swing' the compass stated he was ready and to start the engine. The engine had been running since he boarded. Need I say more?" -- Roy Lupien, Thomaston, Maine - One wouldn't feel a difference on an in-neutral engine attributable to a smoother shaft. They probably installed softer mounts, as well, hence are experiencing less vibration. A U-joint or CV joint/ thrust bearing connection would allow this without the Evolution seal. I believe it dubious that there might be significantly less frictional losses in this than a properly aligned conventional system. The problem on a straight shaft is people don't align them well. The problem with this is it is more to go wrong and expensive. If it were not for the expense, I would do it.

 

The oil doesn't absorb the thrust...the thrust bearings do. I don't have a drawing of the Evolution system but on the Federal shaft log there is a thrust bearing for both forward and reverse thrust .
Mark is correct about most vessels having poorly aligned engines. A wise owner would realign the power plant, stern gear, every time the cutlass and shaft is serviced. They never do and when they do there are not many professional engineers around who can competently align the engine , P bracket, cutlass installation.

For those interested , not long ago there was a good article on alignment in Professional Boatbuilder. Worthwhile photocopying and including into your mechanical ships papers.


As far as friction , Ive seen various numbers thrown around, but my observation is that I can spin the oil bath shaft and prop , when the vessel is out of the water, like a fan .

Cutlass style bearings also are very low friction when correctly installed.

The beauty of the oil bath shaft log, once you forget the price or if someone else is paying for it, is low maintenance , quite rotation, low wear , no exposed SS prop shaft feasting on zinc anodes and no inside stuffing box to service, so a permanent dry clean engine room .

Servicing a conventional stuffing box is a miserable job...they are always dead ended in a black hole, with poor access , in a puddle of oily bilge water with sea snakes and salt water crocodile swarming around, instantly devouring your flashlight and every 10mm spanner you drop in the bilge.

In the end its a budget issue...remember, the quality remains long after the price has been forgotten.

 

Sorry Michael I meant oil bath style.

What size do the Federal systems go up to?

On one megayacht I worked on with 150mm shafts and 1300mm props you could turn the shaft with your hands when in the water..just
Only system I would have.

 

I don't know...most of the Federal gear is semi custom, built on demand , production... I would think the same of the Evolution gear. The system is simple ...I imagine that you could scale up or down and build any size. Ive seen custom home built micro shaft log systems on electric power launches.
One defect of the system is complexity. If you are on a commercially inspected vessel you must pull the shaft and inspect to schedule. This Requires professional shipyard engineers to pull and inspect an oil bath shaft. Many shipyards have no experience with this type.

 

I have done a couple of 5 year inspections and noticed that we only removed the props to inspect the seals, sampled the oil and jacked the shaft up to measure radial clearance and checked shaft to gearbox alignment.
If you have wet shafts I notice the surveyors always have them pulled usually to measure the alignment between the cutlasses and the shaft wear that goes with that
I would say the oil bath inspection ( if not pulled due to leaks etc) is a faster job.

 

Ya , I always challenge surveyors who feel they must pull the whole shaft assemble to inspect. . Ive never seen wear on the shaft and bearings. But Im just a little guy and those guys have the say .

And for the original poster...to save money with a conventional shaft setup . By adding a thrust block you effectively remove shaft thrust and vibration off the transmission. .

Rubber Design BV supplies noise isolation gear for big yachts and shipping.

http://www.rubberdesign.nl/uploaded...pulsion_Equipment/FLYER Stuwdruklagerblok.pdf

Rubber design also supplies oil bath shafts, Isolation mounts, exhaust.... to the yacht industry.

 

Are you looking for something like this (just post #1)?
http://www.boatdesign.net/forums/surface-drives/diy-tunnel-drive-20433.html

It was installed in 2007, not a drop of oil lost, no water entered.

 

I have one installed in a 29' Beals Island Lobsterboat. It was installed during a new build, so I can't tell you how it would compare to a conventional shaft in that vessel. However, my intuition tells me it is a benefit at operating speed; although with the softer mounts I have a lot of vibration at idle. I'm undertaking the process now of trying to address the idle vibration issues - but one theory that I don't fully subscribe to is that with firmer mounts I would not feel that vibration at idle. But I'd probably experience more vibration at speed.

The guys at Evolution are pretty easy to work with. I've called a couple times to confirm servicing procedures and they will talk as long as you want - sometimes longer.

Any specific questions?

 

Yes, BKay. Now we are getting to the meat!
What engine and mounts do you have? When you are experiencing the vibration, in what parts of the structure can you feel, hear, or see it, i.e., can you see the beds vibrate, the hull plating, can you feel it in your feet when you stand next to it? Vibrating at idle, then smooths out... A straight six? Going to be tough to get away from that. Perhaps bump the idle up a bit or softer mounts for idle vibration. A six can be hard mounted and not shake things much off idle.

 

I'll need to pull my notebook down to be specific on mounts - but they were the equivalent to the cushyfloat series specs provided by Evolution. I've got the info at home. The engine is a Yanmar 4JH4-HTE. Vibration at idle is felt through the structure and can be seen by the ripples in the water. I don't have a technical background and I have a pretty low IQ, but I believe the vibration frequency at idle is at just the right point to set up some sort of outrageous harmonic vibration. I advanced the idle about 35 RPM (again, I'll have to check my notes to be sure) and that reduced felt vibration signifantly - possibly by 50-60%. I'm holding off making further adjustments till I can confirm with a Yanmar tech that I'm not creating a problem with the engine or reverse gear by idling too fast - this was a warning provided by Mack Boring when I discussed the idea of advancing the idle.

However, unless I can trace this back to having too soft mounts, none of this speaks poorly of the EMSS. I strongly believe that you need the soft mounts to get benefit from the system at operating speed. It's pretty slick system - but honestly, if money were a big issue it would be the first thing I cut out.