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Old 15-05-2012, 04:43   #1
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Modifications to Horstman tri

I have just purchased a Horstman triStar 45', the raised-coachroof version, and would like to get input on two possible modifications:

1. I would like to have beachability; the rudder is an issue. Can it be changed in shape to a shallower, wider aspect ratio without problem, or has anyone tried a transom-mounted rudder? (Could be made kick-up.)

2. My wife would like to widen one or more berths from current 49" to regular full-size 54". This would involve modifying or removing the "cubby-hole" cabinetry that separates the berths from the main hull. I suspect they are merely cut-outs in a structural box section, and might not be amenable to modification.
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Old 16-05-2012, 07:06   #2
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Re: Modifications to Horstman tri

What did Ed Horstman say ?
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Old 16-05-2012, 07:26   #3
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Re: Modifications to Horstman tri

Regarding the cut out:

I agree with the above... That is a designers question.

Switching to a transom mounted rudder would be fine. What you loose in hydrodynamic efficiency is insignificant in a cruising boat, and you gain MORE directional stability. A transom mounted SKEG/rudder would be best!

You would be better off NOT going shorter but wider on the rudder, IMO. Searunners have used a number of different kick up designs successfully. My favorite kick up rudder btw, is the skeg & rudder combination, (BOTH kick up), that Jim & John designed on my previous project, a SeaClipper 28. It didn't squeak, rattle, or fail in any way. It had only ONE metal part, the 316 grade SS rod. It was perfect! Yes, it's a lot of work to build...

An easier option is a transom mounted, kick up, "balanced" spade rudder... Look up old Searunner designs, or call John Marples for the plans.

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Old 16-05-2012, 22:06   #4
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Re: Modifications to Horstman tri

That is a huge boat....The panel with the cutout is structural, I'm interested to hear what Ed says. 5" doesn't seem worth relocating it. The easy way to make the bunk wider is to extend the overhang in the ama, perhaps with a sliding or drop panel to make it easier to squeeze by.
The kick-up skeg rudder combo was first used by Dick Newick who went on to develop spade only versions. I agree that it would be a neat choice for the boat but an outboard rudder would work well too. I never did figure out why the tristars had the rudder as the low point. The barndoor style you mentioned has good low speed torque but isn't as efficient as a narrow deep rudder.
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Old 16-05-2012, 22:55   #5
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Re: Modifications to Horstman tri

I agree on the bed going into the ama rather than messing with the box section; the drop-down extension (like a table leaf) sounds clever.

Where can I get more info on the kick-up rudder -- size, retraction and reset mechanisms, etc ?
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Old 17-05-2012, 09:52   #6
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Re: Modifications to Horstman tri

I like the Newick under slung kick up rudders. Your Tristar would be a good fit for these. He can be contacted through his email listed on his web site. If you know your way around his designs the Mariners Museum in Newport News Virginia has all his older plans. The are available for the price of copying. You'd want something off one of his bigger boats with the rudder style you prefer. Many are held down with a "stick" that breaks when you hit something or is removed to kick up. This means working off the transom. Chris White has also used this style of rudder. Another approach for a retracting rudder is Richard Woods system. It can be remotely raised and lowered and uses a spade rudder. Check out his web site in the FAQ section and look up rudders. All these systems will take work, remember a outboard rudder will need the transom reinforced if you go that route.
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Old 17-05-2012, 18:55   #7
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Re: Modifications to Horstman tri

The really simple alternative if you can cope with the added draft is of course to add a mini-keel/skeg slightly deeper than the rudder.....if the mattress stays attached to the drop leaf it can be a seat back or bumper for walking past in rough weather....
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Old 01-06-2012, 15:21   #8
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Re: Modifications to Horstman tri

Ed has a kickup rudder option, just call him and tell him what you want to do.
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