Shaft Zinc size

[mhanna]

Does anyone know what the propshaft size is on a 2001 28TE ( ~1.5 inches or so). When I bought the boat the prop was off the boat and now that I am putting together I see there is some room, not alot, just in front of the prop for a shaft zinc. I dont know what size to get, guess I could measure it but I figured I would ask here and see if there were any other suggestions...

Thanks
Matt

[Pitou]

Mhanna

On my '02 the shaft is 1 1/2 inces. Ended up not having quite enough room for a zinc collar / ended up putting on an F Nut with anode. The dealer said there was no room because of engine size (Cummins 370B). So, I guess depending on the engine it can affect the amount of shaft space??? I would buy the collar and you could always return it if there were not enough space then get an F Nut w/ anode.

[JackK]

1 1/2" on my '03.

Pitou - What is an F-Nut?

Every fall I notice that the shaft zinc is gone. I'm not sure how long that thing really stays on. All of my remaining zincs seem to have a little life left in them but the shaft one is always MIA.

Just wondering if there is a better solution for that one.

Jack
_____________________
2003 28 TE Dogonit

[DougSea]

1 1/2" on my '03.

Pitou - What is an F-Nut?

Glad someone else asked the question!

My 97 (1 1/2" Shaft) doesn't look like it has room for a shaft zinc. I know it didn't have one when I took delivery. Rather than a zinc I'm considering installing one of the line cutters. With the outboards I had you could just tilt up the engine if something fouled the prop. The Albin would involve diving. Not so bad on a warm June day - a bit different on a stormy October evening!

[Pitou]

JackK

You caught me on line placing an order to DEFENDER. Annual sale through April 1. Best Deals of the year.

Below is a link to Defender's web-site for the prop nut anode complete system. Unfortuneately the link is not for the F size as defender does not sell that size, but attached for demo.

Only the anode need be replaced annually.The F Nut or size is what fits the 1 1/2 inch shaft. Just remove the cotter pin behind your prop nut and install the anode nut (the big bronze cone). The cotter pin then goes through the anode nut and the anode installs over that. The boys at Standish installed this initially.

My prop nut anode never makes it past August 1st nor does my rudder anode. They get replaced at that time. Trim tab anodes barely survive to the end of October haul out.

One of the things I am ordering is a monitered galvanic isolator by ProMariner. $ 289 sale price / $ 399 everyday at West. The isolator helps to protect thru-hulls, shafts and props from stray low voltage. The zinc loss should be imensely reduced. My dockmate installed one 2 years ago and now he makes it through the season without the need for zinc replacement or haul out. The prop nut anode is a PITA to do underwater.

http://www.defender.com/product.jsp?pat ... &id=150584

[JackK]

Sorry don't want to steal the thread but -

Pitou - Is it a big deal to install the isolator? I've been considering adding one for awhile.

Jack
________________________
2003 28 TE Dogonit

[Pitou]

JackK / you're right / did not mean to hi-jack this thread. It does seem one thing leads to another.

An un-monitored unit is the easiest to install and can be had for about half the price.

Both systems are installed (in between the shorepower inlet and AC Main) to AC ground and DC bonding system block / just 2 posts off the isolator. Cut the AC ground install ring terminals to both ends of cut attach to AC Shore/Ground post on isolator then run a length of wire to bonding block and other end to bonding system post on isolator (again w/ring terminals). Quick, easy, done.(for a boat project)

The monitored system is a bit more work, but monitors the systems operation. The system adds a plug in monitor to the isolator with a plug in cable running to a remote display that I plan to mount next to or below my AC/DC Panel and Genset Panel.

[Tuxedo]

I could not keep a zinc on my shaft at all, because the shaft starts its taper to the prop within the width of a zinc.

So, the yard recommended a shaft brush. It rests on the shaft and connects it to the bonding system. Seems to work just fine, although my zincs don't last over 3 months. I attribute that to the significant tidal flow running through the marina. (In the summer, I need a diver monthly to clean the running gear.)

[RicM]

I installed a galvanic isolator on my old (non Albin) boat last year and noticed an immediate, significant decrease in zinc loss. If my understanding is correct, however, you will only realize this benefit in a marina type environment with other boats close by, and all hooked up to shore power. The point being that the ground wire completes a "circuit" through all the boats connected to shore power and their metal parts (cathodes & anodes) submerged in salt water (electrolyte) creating, in essense, a large battery. As the "battery" generates electricity (wasted, unfortunately), the anodes and cathodes get eaten away, much like the plates in your lead acid battery. An idividual boat at it's own dock, or a boat in a marina that does not lay connected to the shore power 24/7 would not see a significant improvement in zinc life, and the isolator would be a waste of time and $$. I'm no electrical engineer, so excuse me if I've not descibed the situation 100% accurately. The install was quite simple if you are capable of doing regular AC home wiring.

[Merry Kate]

Up to a certain vintage, the 28TEs should have enough room between the cutless bearing and propeller hub to fit a “doughnut” collar, but not the egg-shaped shaft zincs. The newer, high HP set-ups may have such big wheels that there’s less room. Whatever the case, the shaft & prop need to be protected by a dedicated zinc or risk expensive problems. You may be able to machine yourself a collar to fit – zinc’s very soft. A shaft brush is another solution but I’d want mine tied directly into a zinc and not just the bonding system.

http://i172.photobucket.com/albums/w35/ ... 140389.jpg


Ric’s summary is right on: a galvanic isolator protects against the boat-to-boat underwater metal galvanic circuit set up through the common AC shore power ground. It blocks all current up to the approx 1-2V potential drop across the isolator diodes (a typical galvanic circuit is millivolts). However, it does nothing to protect against stray current at any higher voltage, say from 120V shorepower or 12V DC, in which case you have a bigger problem on your hands.

FYI, my ’97 28TE came from the factory WITHOUT the DC ground connected to the AC ground!!! I certainly never had problems with galvanic corrosion, but this is very dangerous and a serious violation of ABYC standards (if AC hot shorts to DC negative anywhere on the boat, everything on DC ground as well as the water around the boat goes to 120V at 30A!) When I discovered that (after running my boat for 5 yrs), I put things right and installed a Promariner 30A galvanic isolator. Easy, except for where I put it - inside the hard to reach space next to the AC breaker panel.

If you own this vintage 28TE I strongly recommend checking your DC to AC ground path with a good ohmmeter. My wiring may have been a mistake at the factory, or more likely just jackleg but in any case invited a tragedy.

[Pitou]

I Went for a swim under the hull in the begining of August and again this past Monday and I just wanted to report in on my zinc loss this season or I should say "Little to no Zinc Loss".

In the past I have had to haul out to replace all anodes by the 1st of August because the prop nut anode is completely gone and nearly impossible, for me anyway, to do underwater and the rudder and trim tab anodes are usually more than 50% reduced. the side benefit of this has been a fresh coat of paste wax on the blue hull. Not this year !

This season with a galvanic isolator installed on the boat for the 1st time all anodes are more than 90% intact. When on my berth I am plugged in all the time needing to run the battery charger for my Norcold DC fridge.

I ended up installing a Newmar Galvanic isolator for $170. Nothing fancy, decided not to be the gadget man for once! It was a fairly easy install by mounting under the cover board on the port side just forward of the shore power inlet. I just cut into the the AC power line leading to the panel and connected the isolator in between.

[Denis]

My zincs seem to last until haul out in October. Im at a new marina this year but every time I SCUBA dive I check under there and so far all looks good. I do not have a zinc on my shaft but it doesn't look like it needs one either. No pitting on the prop or shaft is obvious. Im going to look for a bond wire somehow connected inside the boat.
Doug, I have Spurs line cutters on my shaft, I think our boats are similar, they work very well.
Tuxedo, it is good to see you are still out there and checking in. Let us know if you are back on the water. Denis

[RicM]

The rapid dissolution of zincs is only a concern if your boat is:
A) In salty water
B) connected to shore power 24/7
C) Close to other boats as in A&B

If the above 3 circumstances are met then a galvanic isolator will be a good thing and reduce (but not eliminate) corrosion.

The protection from danger from entangleing that is provided by various shaft spurs is (theoretically) minimal due to the Albin hull design that includes the skeg in front of the prop.

Galvanic corrosion, while not necessarily apparent visually in the early stages is potentially much more destructive ($$$) than fouling with fixed fishing gear (just don't run over it). A shaft & prop will run you what $2000?