Forums › General Discussion › Opinions on the strength of the stern for a windvane

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    • #68351
      Hull152_Patrick
      Spectator

      I’m working along on getting my Hydrovane installed and I’m pretty close to
      the point of actually mounting it, but I’m having some second thoughts about
      the strength of the stern to bare such loads with just the two mounting
      points. The area of the mounting brackets is approximately 36 Sq. Inches
      each and I canwill make the backing plates out of 1/4″ starboard even
      larger than that.

      Question: Is it also neccessary to reinforce an even larger area of the
      stern say by laying up 2 pieces of 1/4″ marine grade plywood with epoxy. I
      say 2 pieces instead of one 1/2″ piece becasue there is some curve back
      there and I think it would be easier that way.

      If I did that, I thought about initially laying in some copper mesh first
      and then the plywood to add to the ground plane for my SSB Antenna.

      I’m curious what you all think about the stern as well.

      Thanks,
      -p

      —
      s/v Deep Playa | Pearson 424 Hull #152 | http://www.DeepPlaya.com | @DeepPlaya
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      Owners no more...
      Thanks Dawn and Patrick!

    • #77288
      madsailor
      Moderator

      Hi Pat,

      Starboard is NOT a backing material – it flexes and compresses. Use
      aluminum, stainless steel, or 1/2″ plywood with epoxy encapsulation. The
      transom is strong enough for what you want to do. Make your backing plates
      approximately twice the size of the fittings, and you should be good to go.

      Bob

      On Thu, Jun 9, 2011 at 8:06 PM, Patrick “Peaboy” Walters <
      > wrote:

      I’m working along on getting my Hydrovane installed and I’m pretty close to
      the point of actually mounting it, but I’m having some second thoughts
      about
      the strength of the stern to bare such loads with just the two mounting
      points. The area of the mounting brackets is approximately 36 Sq. Inches
      each and I canwill make the backing plates out of 1/4″ starboard even
      larger than that.

      Question: Is it also neccessary to reinforce an even larger area of the
      stern say by laying up 2 pieces of 1/4″ marine grade plywood with epoxy. I
      say 2 pieces instead of one 1/2″ piece becasue there is some curve back
      there and I think it would be easier that way.

      If I did that, I thought about initially laying in some copper mesh first
      and then the plywood to add to the ground plane for my SSB Antenna.

      I’m curious what you all think about the stern as well.

      Thanks,
      -p

      —
      s/v Deep Playa | Pearson 424 Hull #152 | http://www.DeepPlaya.com | @DeepPlaya
      _______________________________________________
      maillist mailing list

      https://pearson424.org/mailman/listinfo/maillist_pearson424.org

      —
      Bob Fine
      s/v Pelican
      Pearson 424 Hull #8
      http://thesailinglife.blogspot.com
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    • #77294
      john stevenson
      Participant

      Patrick,
      I’m not sure Bob is aware the Hydrovane is an auxilary rudder vane, not a
      servo (like a Monitor). Essentially you are handing a rudder off the
      transom. I think it would require significant beefing up of the transom for
      that load. Then again I’m not an engineer so I don’t know how much beefing
      it would require. The only thing I know is the previous owner mounted a
      boarding ladder on the transom with plywood backing plates and my 250 Lbs
      managed to produce hairline cracks in the transom.

      Regards,
      John Stevenson
      http://www.svsarah.com

      On Thu, Jun 9, 2011 at 8:18 PM, Robert Fine wrote:

      Hi Pat,

      Starboard is NOT a backing material – it flexes and compresses. Use
      aluminum, stainless steel, or 1/2″ plywood with epoxy encapsulation. The
      transom is strong enough for what you want to do. Make your backing plates
      approximately twice the size of the fittings, and you should be good to go.

      Bob

      On Thu, Jun 9, 2011 at 8:06 PM, Patrick “Peaboy” Walters <
      > wrote:

      I’m working along on getting my Hydrovane installed and I’m pretty close

      to

      the point of actually mounting it, but I’m having some second thoughts
      about
      the strength of the stern to bare such loads with just the two mounting
      points. The area of the mounting brackets is approximately 36 Sq. Inches
      each and I canwill make the backing plates out of 1/4″ starboard even
      larger than that.

      Question: Is it also neccessary to reinforce an even larger area of the
      stern say by laying up 2 pieces of 1/4″ marine grade plywood with epoxy.

      I

      say 2 pieces instead of one 1/2″ piece becasue there is some curve back
      there and I think it would be easier that way.

      If I did that, I thought about initially laying in some copper mesh first
      and then the plywood to add to the ground plane for my SSB Antenna.

      I’m curious what you all think about the stern as well.

      Thanks,
      -p

      —
      s/v Deep Playa | Pearson 424 Hull #152 | http://www.DeepPlaya.com | @DeepPlaya
      _______________________________________________
      maillist mailing list

      https://pearson424.org/mailman/listinfo/maillist_pearson424.org

      —
      Bob Fine
      s/v Pelican
      Pearson 424 Hull #8
      http://thesailinglife.blogspot.com
      _______________________________________________
      maillist mailing list

      https://pearson424.org/mailman/listinfo/maillist_pearson424.org

      _______________________________________________
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    • #77305
      Anonymous

      Pat,

      I mounted a large external rudder on my transom when I installed the
      Auto-Helm windvane. To beef up the transom, I made up large 1/4″
      aluminum backing plates (photos attached). I believe you’d damage the
      transom if you don’t do something similar. (Note the necessity to bend
      the backing plates a little to match the camber of the transom. If you
      get them close, they’ll finalize their shape when they’re snugged down
      with the thru-bolts.)

      The installation has proven sound so far over a few thousand miles of
      offshore sailing.

      Tor


      Silverheels, P-424 #17
      http://www.silverheels.us


      Quote:

      Original Message


      Post generated from Pearson424 Forum using Mail2Forum

    • #77306
      Anonymous

      Pat,

      (This time with the photos!)

      I mounted a large external rudder on my transom when I installed the
      Auto-Helm windvane. To beef up the transom, I made up large 1/4″
      aluminum backing plates (photos attached). I believe you’d damage the
      transom if you don’t do something similar. (Note the necessity to bend
      the backing plates a little to match the camber of the transom. If you
      get them close, they’ll finalize their shape when they’re snugged down
      with the thru-bolts.)

      The installation has proven sound so far over a few thousand miles of
      offshore sailing.

      Tor


      Silverheels, P-424 #17
      http://www.silverheels.us


      Quote:

      Original Message


      Post generated from Pearson424 Forum using Mail2Forum

    • #77312
      Herbc
      Participant

      Our stern had 3 mounts, just removed, and the top near center was crinkled all around. I would vote metal or ply/epox backing.

    • #77317
      Hull152_Patrick
      Spectator

      that’s about what i was thinking… but where do you store that big press on Silver Heels. 😉

      Sent from my iPhone

      On Jun 11, 2011, at 4:52, “Silverheels” wrote:

      Pat,

      (This time with the photos!)

      I mounted a large external rudder on my transom when I installed the
      Auto-Helm windvane. To beef up the transom, I made up large 1/4″
      aluminum backing plates (photos attached). I believe you’d damage the
      transom if you don’t do something similar. (Note the necessity to bend
      the backing plates a little to match the camber of the transom. If you
      get them close, they’ll finalize their shape when they’re snugged down
      with the thru-bolts.)

      The installation has proven sound so far over a few thousand miles of
      offshore sailing.

      Tor


      Silverheels, P-424 #17
      http://www.silverheels.us


      _______________________________________________
      maillist mailing list

      https://pearson424.org/mailman/listinfo/maillist_pearson424.org

      Post generated from Pearson424 Forum using Mail2Forum

      Owners no more...
      Thanks Dawn and Patrick!

    • #77318
      Anonymous

      It’s an inflatable press. Stores in a shoebox.

      Actually, on another occasion (before I discovered that beautiful press
      in the boat yard) I bent a large plate of that same 1/4″ aluminum by
      laying it on the ground supported by 2×4’s along either edge, and
      running over it with my car. Two passes bent the plate just enough to
      match for foredeck’s camber perfectly!


      Original Message


      Post generated from Pearson424 Forum using Mail2Forum

    • #77372
      Anonymous

      I installed a Sail-O-Mat on Easy Reach. After bolting on the single bracket that held the unit on the transon, I noticed considerable oil-canning. I then added to long aluminum battens, 1/8 thick by 1 1/2 inches wide by 3 feet or so long and rebolted the bracket through them. Since I have long since sold her to Alan Tershko, I don’t rember what else I did, but I seem to remember there were other bolts already in the transom that I used to stabilize the lower ends of the battens. Because I used 1/8 stock, bending to the cuirve of the transom was easy. The rig held up from Key West to Belize, Roatan, and back to Key West. I found the wind driven device almost useless in the lakes and, of course, the Erie Canal. The best use was in the trade wind zones south of Isla Mujeres.
       
      Norris Larson

      — On Sat, 6/11/11, Silverheels wrote:

      Post generated from Pearson424 Forum using Mail2Forum

    • #77373
      Hull152_Patrick
      Spectator

      Thanks everyone for the suggestions, very helpful!

      Here’s what I’m doing….

      My external platesbrackets are approximately 9″4″ (they’re not really
      rectangular). Which are sitting on starboard pads. The top bracket is on a
      1/2″ pad and has very little shapingtaper to match the hullalign the
      windvane. The bottom bracket has an 1″ to 1/2″ starboard wedge that is
      shaped to properly align the brack and thus the windvane. That took a day to
      sand by hand!

      On the inside, I’m using 13″x8″x1/2″ Marine Grade Plywood that I sanded to
      match the interior hull shape. Dawn then sealed them in epoxy. On top of
      that will be 316 SS backing plates that are 6″x10″x1/4″ and SS fender
      washers & Nylocks.

      I think it will be pretty beefy, if I notice any issues, I’m going to glass
      in a full sheet of 1/2″ marine grade plywood or coosa board.

      -p

      —
      s/v Deep Playa | Pearson 424 Hull #152 | http://www.DeepPlaya.com | @DeepPlaya

      On Mon, Jun 20, 2011 at 12:17 PM, norris larson wrote:

      Quote:
      I installed a Sail-O-Mat on Easy Reach. After bolting on the single bracket
      that held the unit on the transon, I noticed considerable oil-canning. I
      then added to long aluminum battens, 1/8 thick by 1 1/2 inches wide by 3
      feet or so long and rebolted the bracket through them. Since I have long
      since sold her to Alan Tershko, I don’t rember what else I did, but I seem
      to remember there were other bolts already in the transom that I used to
      stabilize the lower ends of the battens. Because I used 1/8 stock, bending
      to the cuirve of the transom was easy. The rig held up from Key West to
      Belize, Roatan, and back to Key West. I found the wind driven device almost
      useless in the lakes and, of course, the Erie Canal. The best use was in the
      trade wind zones south of Isla Mujeres.

      Norris Larson

      — On Sat, 6/11/11, Silverheels wrote:

      Post generated from Pearson424 Forum using Mail2Forum

      Owners no more...
      Thanks Dawn and Patrick!

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