Page 3 of 3 FirstFirst ... 23
Results 71 to 82 of 82

Thread: H28 Genesta

  1. #71
    Join Date
    Jul 2007
    Location
    Wongawallan Oz
    Posts
    17,024

    Default Re: H28 Genesta

    Quote Originally Posted by Phil Y View Post
    Id want to see a zinc on the shaft, and on the hull. But I think plenty of owners use anti foul on their props and shafts. I've seen plenty of debate about whether it works in terms of stopping growth, vs things like prop speed, virgin olive oil beeswax etc. Absent other factors, like stray Marina currents etc, is antifouling on the prop really an issue in terms of galvanic corrosion?
    As I mentioned, I’ve replaced a few shafts, struts and props because they had become pitted from electrolysis and which were anti fouled with a copper based antifoul, who knows for how long and what other factors were at play?. They may have had variations of a combination of all sorts of things but the direct advice from the prop and shaft suppliers - the “experts" that specialised in supplying, machining and balancing new props and shafts was that they should not be anti fouled directly with a copper based antifoul because it would cause a galvanic action and electrolysis.

    Copper based antifouling can be applied over a vinyl or epoxy “insulation” coat and is even applied to aluminium hulls that way, but how well either will hold to a spinning shaft and prop then becomes the question..

    I’m no expert on the matter and won’t argue with anyone who differs, I can only go on what I’ve seen through experience and been advised directly for mostly commercial applications by the guys who should know better than anyone.

    Regardless of the antifoul though James - the anode is essential to prevent galvanic action between the stainless shaft and fittings and the bronze strut and prop’ - it is an imperative. You can likely get a two piece one to suit your shaft size that you can bolt on over the shaft but you’ll need it to sit on bare stainless, not over the antifoul



    Measure your shaft behind the engine and you could fit it in water without hauling out if you have some dive gear (or a long snorkel.....)
    Last edited by Larks; 05-26-2018 at 07:46 AM.
    Larks

    “It’s impossible”, said pride.
    “It’s risky”, said experience.
    “It’s pointless”, said reason.
    “Give it a try”, whispered the heart.

    LPBC Beneficiary

    "Keep away from people who try to belittle your ambitions. Small people always do that, but the really great make you feel that you, too, can become great!"

  2. #72
    Join Date
    Nov 2004
    Location
    Port Townsend WA
    Posts
    14,445

    Default Re: H28 Genesta

    Larks is right. A replaceable anode prop nut is another way to go. This can be done in the water but I think a zinc collet on the shaft is even mo-bettah!
    Jay
    Last edited by Jay Greer; 05-26-2018 at 05:03 PM.

  3. #73
    Join Date
    Apr 2010
    Location
    South Australia and Tasmania
    Posts
    21,467

    Default Re: H28 Genesta

    Thanks Greg. Not really arguing, just clarifying as that came as a bit of a surprise to me.

  4. #74
    Join Date
    Jun 2017
    Location
    Brisbane Australia
    Posts
    67

    Default Re: H28 Genesta

    Thanks heaps for your advise.
    The previous own has told me that there is a barrier coat between the antifoul, shaft and prop.
    He had advise that he didn't need the anode which is why there isn't one on there currently. something about it being a timber boat.....
    I think I will put one on the shaft now.....
    Would it be worth hanging one in the water like you used to on aluminium boats until I can get under and put one on the shaft?
    I've also heard about putting a piece of balsa wood in the water next to the boat so any worms ect would go for that wood over you boat.
    There isn't any visible pitting or corrosion on either the prop or shaft but would the old paint cover that?

  5. #75
    Join Date
    Jul 2007
    Location
    Wongawallan Oz
    Posts
    17,024

    Default Re: H28 Genesta

    Quote Originally Posted by James Chilman View Post
    Thanks heaps for your advise.
    The previous own has told me that there is a barrier coat between the antifoul, shaft and prop.
    He had advise that he didn't need the anode which is why there isn't one on there currently. something about it being a timber boat.....
    I think I will put one on the shaft now.....
    Would it be worth hanging one in the water like you used to on aluminium boats until I can get under and put one on the shaft?
    I've also heard about putting a piece of balsa wood in the water next to the boat so any worms ect would go for that wood over you boat.
    There isn't any visible pitting or corrosion on either the prop or shaft but would the old paint cover that?
    The previous owner was kidding himself on his "no anode for a timber boat" philosophy. The zinc anode, being the least noble metal in the area, is there to essentially absorb the electrolytic current that is created in the salt water between the bronze of the strut and prop' and the stainless steel propellor shaft, as well as the fastenings and rudder pintles and even the hull fastenings and keel bolts.


    Hanging a couple of anodes around the hull won’t do any harm and they’re cheap enough, but they won’t replace the shaft anode that you need.

    Hanging the anodes is popular when berthed by something that is leaking a lot of stray current or creating a strong electrolytic current - such as a steel pier or some steel or aluminium hulled boats. But that’s hard to pick unless you see your own anodes being chewed up much faster than they have elsewhere - and with no anodes you wouldn’t know.

    This, from a quick google search, looks like it may be a useful read for you: http://www.boatus.com/boattech/artic...-corrosion.asp
    Larks

    “It’s impossible”, said pride.
    “It’s risky”, said experience.
    “It’s pointless”, said reason.
    “Give it a try”, whispered the heart.

    LPBC Beneficiary

    "Keep away from people who try to belittle your ambitions. Small people always do that, but the really great make you feel that you, too, can become great!"

  6. #76
    Join Date
    Feb 2006
    Location
    Space
    Posts
    2,381

    Default Re: H28 Genesta

    Quote Originally Posted by Larks View Post
    James, so as not to hijack Jay’s thread, here’s a version of a galvanic table worth looking at. Although on Jay’s thread Paul G has never heard of copper antifouling eating a stainless shaft or bronze struts, this sort of electrolysis from the galvanic action between the copper in the antifoul, the stainless steel and bronze is indeed a quite real and regular occurrence and I could tell you of quite a few instances of replacing shafts, struts, props and nuts that I have had to deal with when managing a commercial marine engineering business.

    Whether or not there were any "complicating factors”, it doesn’t take much for galvanic action to have an effect, especially where there is no sacrificial anode present, and you will more likely than not soon have pitting in your shaft, prop and strut.
    Larks, I have seen plenty of boats with antifouled drives that suffer no ill effect including mine. However I use an epoxy primer, perhaps they do as well?
    whatever rocks your boat

  7. #77
    Join Date
    Nov 2004
    Location
    Port Townsend WA
    Posts
    14,445

    Default Re: H28 Genesta

    I would be prone to removing the upper/inner layer of that cracked frame and making a long gentle white oak scarf insert set in G/flex and braced against the overhead till the glue sets. This would require removal of the fastenings from without as well. However, they may be short enough to be cut off from within! If the fastenings can be cut off at the half way point with a few threads holding, you might be able to wait until your next haul out to deal with new fastenings. Rivets will be less invasive to the structure in this case.
    Then there is the choice of laying a sister rib along side. Do not use plywood as it will create a hard spot. I would use laminated oak with a long taper on the ends. Riveting is better than using screws for this. This will require a haul out to accomplish. The first fix may allow you to work only from the inside and can be done in the water if the existing fastenings can be cut to fair with the half thickness of the outer layer of the frame.
    Jay
    Last edited by Jay Greer; 02-22-2020 at 02:48 PM.

  8. #78
    Join Date
    Nov 2004
    Location
    Port Townsend WA
    Posts
    14,445

    Default Re: H28 Genesta

    Quote Originally Posted by Paul G. View Post
    Larks, I have seen plenty of boats with antifouled drives that suffer no ill effect including mine. However I use an epoxy primer, perhaps they do as well?
    Wooden boats are prone to having different potential for conductivity with various dissimilar metals than are fiberglass hulls. Various accoutrements such as wires below the water line for such items as depth sounders and automatic bilge pumps can raise all manner of problems with a wooden hull! One way of checking this out is to use a multimeter that reads in micro amps to check for any weird stray current flow. This can be done by attaching one lead to a keel bolt or other metal component that connects to the outer surface of the hull with micro current flow potential and hanging the other connector lead to the meter over the side in the water. This lead should be attached to a conductive plate such as a strip of copper or other conductive material. I have even seen one person use a silver plated spoon out of a kitchen drawer! This will show if any current flow is in action with your hull. .05 or less is said to be safe. More than .1 seems to be cause for the need of greater investigation. Certainly 1 amp is cause for great concern! Our wooden hulls can support current flow. While some experts advocate bonding of metals such as keel bolts and through hulls. I, for one have never found bonding to be a "Get out of jail free card". So, unless you are an expert on the subject, I would leave the tracing of ionic flow problems to one who is a specialist. Certainly drop chords and electrical charging of batteries in a marina is something that is a real potential problem for a wooden boat. So, it is a good idea to keep your eyes pealed for that kind of potential disaster!

    One of my friends who knows a lot about this electrolysis horror is Chris McMullin whol lives in NZ and has the McMullen Wing Co. there. Although Chris claims to know nothing about wooden boats, I claim to differ with him on that point. I know for a fact that he knows a bit about wooden boats, certainly more than I do! Chris is, defiantly, against the use of zinc anode attachments to wooden hulls as it will produce and allow sodium hydroxide to work into the wood and destroy the fibers, literally turning the wood into pulp! In fact this is one to the ways that paper mills use to break down wood pulp before it becomes paper.

    If you would like to read some of Chris's comments on his own research into the subject of electrolysis and wooden boats, you can check it out here. https://waitematawoodys.com/2016/11/...at-looks-like/
    Jay
    Last edited by Jay Greer; 05-28-2018 at 02:09 PM.

  9. #79
    Join Date
    Jun 2017
    Location
    Brisbane Australia
    Posts
    67

    Default Re: H28 Genesta

    My partner took the boat out the other weekend for the lady skippers race in Brisbane.
    Unfortunitly I was away doing an offshore rece, and as usual the best pictures of your boat you have don't have you on it!
    There was bugger all breeze so they didn't finish but fun was had I was told.

    [IMG]IMG_1700 by James Chilman, on Flickr[/IMG]

    [IMG]IMG_1702 by James Chilman, on Flickr[/IMG]

    [IMG]IMG_1703 by James Chilman, on Flickr[/IMG]

  10. #80
    Join Date
    Nov 2004
    Location
    Port Townsend WA
    Posts
    14,445

    Default Re: H28 Genesta

    Looks like a proper boat and crew! I see you have a variation on the original rig as designed by LFH. The upper main shrouds run all the way to the masthead which allows you to fly that masthead chute as well as the mast head jib. While this allows support for the upper portion of the mast and avoids breaking it, most of the time. There are pros and cons to this kind of a rig for a wooden boat such as the H28. Having a masthead rig places extra stain, much more than a fractional rig, on the hull, especially the stem and forefoot! This, in general is fine in light to medium airs but not that good when the wind really pipes up. The main mast will take a kink between the spreaders and mast head cap which results in foreshortening the height of the main mast and loss of efficiency for the jib. Adding a set of running backstays and flying a fractional 3/4 jib is better for the boat and will keep her on her lines as well as give greater speed. This is why a fractional rig was drawn by LFH for the H28 is more reliable for a cruising boat. Less strain on the entire boat! A compromise is to add a set of jumper stays to support the mast when flying a chute on a broad reach and allows for a longer jib luff as well. The higher aspect ratio is a plus for upwind work and the rig then becomes 7/8 in height and gives the best of two worlds. I am not being harsh in this comment as former owners broke "Bright Stars" main mast three times before we bought her!
    Jay
    Last edited by Jay Greer; 02-22-2020 at 03:12 PM.

  11. #81
    Join Date
    Aug 2010
    Location
    BC Coast
    Posts
    4,201

    Default Re: H28 Genesta

    Nice....!

  12. #82
    Join Date
    Apr 2015
    Location
    St. Helens, Oregon
    Posts
    4,966

    Default Re: H28 Genesta

    Spinnaker and stays'l pulling nicely Looks like waaay too much fun!

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •