Aluminium alloys vs Stainless steel - Neptune windvane

rsallo

rsallo

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Hi,

I'm looking at the Neptune windvanes as they seem to be cheaper than the well-known brands like Monitor, Windpilot, etc. Does anyone have first (or second) hand experience with them?

One of the things I've seen in the prod specs is that some parts are aluminium rather than SS:

Castings: All LM 25 aluminium alloy
Tubes: Aluminium grade 6063, with anodized finish
Shafts: Grade 316 stainless steel

I know nothing about aluminium alloys, do they corrode quicker than stainless steel? Are they a good option for a windvane, with all the waves and spray constantly hitting it?

Thanks!
 
No experience of Neptune gear but some with ss fittings in aluminium castings and a marine environment. Basically, the aluminium corrodes around the ss (aided by salt water) and expands locking the ss in place. If it's a ss bolt threaded into alluminium the thread will disintigrate with use (oceanographic current meters opened up on a monthly basis).

One of the criticisms of the Aries gear is that it is almost impossible to dismantle for bearing replacement after a lot of use because the alluminium casting corrodes around ss shafts and locks them in place. My current boat came with a rebuilt Aries - and it bore the scars of a heavy hammer on the end of some of the ss components. The manual recommends dismantling one component with a single blow from a heavy hammer rather than tapping it out.

The new owner of the Aries was very pleased to get it, as I replaced it with the all ss and bronze Monitor gear from my last boat (the Monitor is on it's third boat and has at least one Atlantic circuit and a new set of bearings to its credit).
 
Wind vane

I think you will find there is no problem in practice with the components of the wind vane. It seems to me that vanes do not last long anyway. Birds are a major problem. I make my own out of fibreglass or carbon fibre, resin stainless steel shaft but if I get a few seasons I ma lucky.
Any ss bolts into Al can be helped with Duralac or grease of any sort to minimise corrosion. olewill
 
Windpilot has very similar materials specification. The static parts are all aluminium alloy castings and most of the moving parts are stainless steel. Some aluminium alloys are intended for marine use, others are not. It's all a matter of correct specification. My Windpilot was about 12 years old when I sold it, no corrosion whatsoever, despite having been aboard for all of those years, and well used.
 
I guess you need to do regular maintenance on a gear with mixed materials, although I don't have direct experience. Everything else on a boat needs looking after - anyone who doesn't clean and lube the stanchions and bases will know!

I was more concerned when the brochure says the gear can be used as an emergency rudder. That just isn't possible, it goes against the whole design principle of a servo pendulum. In which case either the UK dealer knows nothing about the gear he's selling or he's working through a large supply of old brochures.

Rob.
 
I have one of these gears but have not used it yet, so can't help you there.
It seems well put together and (as vyv cox has pointed out) is a simailar spec, and weight, to the more costly Windpilot.
I have seen comments suggesting that it looks rather fragile, but alongside some gear it looks like the Forth Bridge to me. It is difficult to find people with this kit perhaps because they are a small player in a niche market, however one chap with a Sadler 34 posts on these pages and seems pretty well pleased.
Give them a ring, the chap you will speak to is Trechard Bowen, I believe he is the owner, designer , manufacturer (in SA) and user of the gear, and is very helpful.
I guess if you want stuff of this weight and price you have to accept the composite construction, which is well proven and should be perfectly satisfactory if soundly designed and looked after
PS
On the emergency rudder thing. I have seen other gears make this claim but they offer a larger blade for the job and (I think) a means of directly canting them using lines. It is proably, at best, speculative, but maybe better than nowt.
 
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Purely regarding materials, stainless steel is indeed superior to any aluminium with regard to corrosion resistance in air or open water where free oxygen is present. but is much heavier and infinitely more expensive. It's a matter of good engineering practice and cost. What is your mast made of? Do you have an outboard motor? What is that made of?
The correct grade of aluminium (such as the grades you mention) are adequate and if you have anything screwed into it it should be assembled with Duralac or similar as others have suggested. If so.... no worries!
 
macd said:
The Neptune is uncannily similar to the Windpilot in many other ways, although far be it from me to draw any inference from that...
Click to expand...

Yes, it is a strange coincidence, isn't it! Must say that fromn the photos on their website everything seems to be built rather more lightly than the Windvane, as if the castings were all shaved down and then re-cast.

The auxiliary rudder claim is rather misleading, I don't see how that can be true.
 
Appologies

William_H said:
I think you will find there is no problem in practice with the components of the wind vane. It seems to me that vanes do not last long anyway. Birds are a major problem. I make my own out of fibreglass or carbon fibre, resin stainless steel shaft but if I get a few seasons I ma lucky.
Any ss bolts into Al can be helped with Duralac or grease of any sort to minimise corrosion. olewill
Click to expand...

Sorry I really thought the question was about wind pointers on mast top but apparently more about self steering gear. olewill
 
It is possible to have a trouble free aluminium Windvane but the fact is most have corrosion problems.Being made of stainless doesn't necessarily make it more expensive.I have a Monitor that behaves brilliantly and that,when my boat got rammed by another,was very easy to repair because of it's stainless steel construction.A few touches with the hammer here and there and some minor welding and it was as good as new.
With an aluminium construction things get complicated and expensive very easily.
And bits don't get seized due to corrosion on the Monitor.I had to disassemble it for welding and had no problems at all.
 
The Neptune windvane seems to have advantages in terms of easily removing it (eg while at harbour). I saw an Aries windvane installed on stern of a boat once, and while it looked completely bulletproof it didn't look like it would be feasible to take it off routinely.

Any comments on the desireability of this function ? I guess it's a trade-off between being permanently in the way vs strength in operation but I was thinking of the situation where you want a stern ladder in port but a windvane at sea.

Boo2
 
Boo2 said:
The Neptune windvane seems to have advantages in terms of easily removing it (eg while at harbour). I saw an Aries windvane installed on stern of a boat once, and while it looked completely bulletproof it didn't look like it would be feasible to take it off routinely.

Any comments on the desireability of this function ? I guess it's a trade-off between being permanently in the way vs strength in operation but I was thinking of the situation where you want a stern ladder in port but a windvane at sea.

Boo2
Click to expand...

For me the ability to remove is desirable as I don't always want the windpilot in place, especially when sailing in the Solent when the tiller pilot makes more sense. With the removal of two bolts my windpilot can be taken off and stored ashore/onboard.
 
Our Windpilot was removable simply, by loosening one bolt and withdrawing the fixed shaft from its housing. In practice this was a tricky manoeuvre hanging over the transom. Once removed it is a cumbersome device, with several parts all rotating around one axis. It can't be stored very easily without dismantling it. So overall it was easier to leave it where it was. Which is why I sold it when we found berthing stern-to to be our preferred option in the Med.

The Neptune appears to have a rather more complex mounting arrangement but it is clearly very similar to the Windpilot in other respects.
 
vyv_cox said:
The Neptune appears to have a rather more complex mounting arrangement but it is clearly very similar to the Windpilot in other respects.
Click to expand...

Actually, one of the Neptune mounts looks very similar to what you describe. I was wondering if it would be possible to fit it through the rungs of a transom mounted boarding ladder but it's had to get an idea of scale from the pictures.

Boo2
 
Boo2 said:
Actually, one of the Neptune mounts looks very similar to what you describe. I was wondering if it would be possible to fit it through the rungs of a transom mounted boarding ladder but it's had to get an idea of scale from the pictures.

Boo2
Click to expand...

Yes I agree, that one looks surprisingly similar (!) to the Windpilot one I had. Some others on the Neptune site look quite different.

Can't comment on whether it will fit through a ladder, as every installation ios different. It would be very tedious to remove the steering gear every time you wanted to use the ladder to access the dinghy.
 
aluminium stainless steel

Hi

there are several different type of aluminium alloy, and there are some, the 5000 series if i remember well that is called a "marine" grade, which means that it's alloyed and is more resistant in a marine environment.
Also SS can suffer from corrosion in a marine environment if is not the correct type of SS.
galvanic corrosion is a possibility but depends on many factors like the area ratio of the metals.


http://aluminium.matter.org.uk/aluselect/02_corrosion_browse.asp

Vitt

corrosion & rust prevention
 
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