Kickup rudder critique

0012 seems to be a common section. I for one would love to see whatever you care to share. Looks are subjective I guess but I don't mind the art deco lines. At least they don't look like a block of flats (apartments).

Ultimately I rejected the Horstmans because the accommodation is all in one. Trimarans like monos give little privacy and separation until you go very big. I'm also not fond of the masthead rig.

I would be especially interested in a sailing report when you get it wet. Either way good luck

 

Regardless of any structural issues, if the concern is to get a more balanced rudder (lighter helm/less 'feedback force') you put the CE of the foil in front of the pivot axis of the pintles and gudgeons. Moving the top pintle back to make for a vertical rudder on a raked transom does this. The equivalent could be achieved by putting more of the rudder area in front of the pivot axis on the sloped transom of the Horstman. A Really Rough rule of thumb is 2D foil sections have a moment center 25% behind the leading edge, which means it would be 100% balanced (no feedback, which is not desirable).

 

I had my foils CNC'd from laminated wood blanks I provided. Foil shape is NACA 63A010. Chord is 320 mm at the top and tapers down to about 250mm just before the tip radius. Its 30mm thick and 800 long, built of ply (in hindsight it should of been cedar) glassed with 10oz uni and boat cloth. Well its meant to be 800 long, but when I cut the blank it was easy to make it 100mm longer. So I did. When it broke after about 3 years I was able to reshape the top (and also added a crap ton of double bias) and re-use it. So now its 750mm long and I haven't noticed any difference loosing the 150mm, its still nicely balanced and steers fine.

Please start a thread and post a few photos - it would be great to see more of a more traditional foam build as opposed to a flat panel kit type. The extended transom looks good IMO and could easily be cut down to half height for a boarding platform if so desired.

 

I just verticalized the transom on my buccaneer. I'm building a rudder setup that is dagger style so it can be raised in shallow water, and also kicks up in a grounding. A regular swing rudder sucks to steer in a raised position, which sometimes I need to be when getting back to my slip. It'll have an aluminum cassette case, an epoxy/fiberglass coated wood rudder, and a false transom type setup to kick up. I'm also thinking about future t-foil on the rudder. But that's a different future conversation.

 

Freddyj, could you share some pictures/drawings of your setup?

 

My setup is still in progress. But here is a crappy drawing of what I have in mind. The hinge is a full width piano hinge and I will have to have a way to prevent side twisting.

 

My seaclipper 16 uses the false transom with the hinge at the top. The hold down line works a little differently though. I can get you a picture if you're interested.

 

That would be great!

 

Looking at the design drawing I would be concerned about the single central hinge and the hold down line.

On the Seaclipper for example, the false transom runs almost the entire width at the top with hinges at each corner with the hold down line coming into the back at the bottom.

With a single central hinge, I would worry about side loading and twisting, and with the hold down as a fence, too much potential movement.

The rudder setup on my Tri is fixed into a plug that fills a slot in my transom to handle side loading and then uses a removable cross pin at the top to act as a pivot with a hold down line coming through the back. The rudder assembly can be pinned at a higher height for shallow water conditions, and can swing up if struck. It’s a little different approach but offers the same needs.

I’ve often wondered if one could use an outboard jack plate setup along with a swing up to accomplish the same goals of being able to adjust usable rudder draft while having strike protection. If Jack plates can handle the loads of an outboard motor used to propel and steer, I don’t see why it couldn’t be used to hang and handle the loading of a swing up.

 

There was a 28' Horstman in New England with pictures on the web of the boat on a mooring , I can't find my picture of the stern with a look at the rudder but I think it was a dagger board rudder . I never could get in touch with the owner . There was a 28' in Baytown Texas , and there are pictures of that boat in the Gallery of Sailing Texas ? under tri-star . It had a spade rudder I think with an outboard on the transom , she was hurricane salvage with a hole in her last picture I saw of it . I ran across a 31' foam built in Florida that was in an old sale post , no info on that boat , i never could locate it . There was a Horstman listed as a 36 for sale in Va, I am not sure it started out as a 36 . There are pictures of that boat somewhere on this forum , might be a shot of a rudder . When it came past us going up the river everyone stopped work to look at her . The roof had been modified , it sort of had a bat mobile feel , it was sharp looking and fast going against the current . When it came back down it was still fast , but butt ugly with the top modified again , thats when I was able to get pictures . Ed supplied the kick up rudder with my 31 plans , not sure if it is a standard rudder design for smaller boats or just on request . I was planning on a dagger board rudder , I bought renicell for the transom to beef it up .

 

Scuff , my kick up rudder looks to be the same as yours , drawing # is T 75 - 18 , no model listed , probably a standard design for smaller designs .

 

Rberry I believe you are right same drawing. I've actually got the plans for the 36' less the full size patterns.
Freddyj, here are the pics of the false transom they are pretty much as solgato described. We got snow here so may be a couple days before I get pictures of the transom.
The first pic is the backside. The hole in the bottom right with the line coming out of it is the hold down the false transom is the same size as the actual transom less enough to fit into the recess. I agree on the hinge(s) they should be as far apart as possible and beefy. I ordered mine online. On the actual transom is a mating hole for the hold down. You glue a piece of stainless tubing bent up to the angle you want. You extend that well above the waterline by gluing a piece of rigid tubing over it. The sc16 has a slot in the aft deck the line comes out of to a cleat on the aft beam. HTH.

 

Very similar to what I've got in mind. Thank you for the photos.

 

Here's what I have

 

Looks good, nice job!

Definitely doesn’t have the “hardware store” look of other examples.

Is the locking pin at the bottom designed to shear when overloaded to allow the rudder to kick up?