Reynolds 21 w/New TheMightyHobie18 Rudders

Our test day was only 5mph winds, but this weekend they are calling for 11mph winds, I will have a better test on Saturday! But man i love these rudders, coming into the beach is so much nicer and even going out is nice! While going out you lift and pull down now I am half a Hobie cat! LOL Love love Love love them I hope they continue to make me happy. My other rudders were huge bats! they would jerk when you made a turn and in high winds i had to use 2 hands to hold the cross bar


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Those are the "old style" rudder castings. Those castings were notorious for not kicking up properly when hitting the bottom. You have to make sure that the roller pin & hook are well lubricated with grease and that you don't put too much preload on the cam spring. There is a fair amount of discussion about those castings on the Hobie 18 forum at the Hobie website. If the rudders don't kick up, you will either crack out the lower casting, rip the gudgeons out of the transom, or break the rudder pin.

Also, those look like old lexan rudder blades. They may not be up to the task of handling the load of a 21 foot cruising cat, especially if they've sat out in the sun for many years. Those blades have been known to snap off just below the casting. A composite rudder may be a better choice (it will certainly provide better performance).

Just a couple things to consider.

sm

True, to be fair the old style with the metal (permanent) cams worked for a couple of decades before they started failing miserably.

Basically they work until that time that they don't, so I always advise anyone with the old (pre-1987) castings to assume they will not kick up automatically.

Otherwise

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Thanks guys, yes i well lubricated them really good, plus i do pull them up before the beach anyways.. I hope they don't snap when i'm sailing at great speeds that would suck! I guess i will keep that in mind and look for better blades to fit those castings.. I know a few of guys with H18s that use these rudders in my group. Do you guys think I would gain a knot of speed with these ? I did feel a little more increase in power in the little breeze we had. Who knows i will find out this weekend we all sail around each other and chase each other for fun, I would always get dusted and i felt that i was dragging something.. LOL But i have to say you guys know your rudders for noticing that one!

Do you guys know if you can make your own rudder blade and how would you do it? maybe i should look into doing that with spare time and maybe out of some hard wood , then maybe fiberglass it?

Sure you can
if you are a master technician with a great understanding of underwater foil dynamics -

otherwise, you will probably be much better off getting a new or used pair of EPO's



Really hard to say - All other things being equal

depends on how bad of condition your old ones were,
if everything was aligned optimally/correctly,
and if everything is now aligned optimally/correctly,

and if this (rudder) shape is a more favorable shape (and condition) for your boat .. then yes! you should be much faster! enjpoy!

I've been thinking about building some foils (namely a set of daggerboards), but I always stop when I start adding materials costs up. I have the know-how and the expertise to design and build a board or rudder that is the equal of any production board built anywhere, I can even go to the extent of full carbon autoclaved high modulus carbon boards that have CFD and FEA behind them, which is more than most builders do, but they also usually have decades of "this works" experience to backup their laminate schedules. The reality is to build a board or rudder on par with a factory finished board requires aluminum tooling and a great deal of expertise. It isn't something I would try at home with no experience at all. That being said, you can likely hand shape a cedar cored rudder that is the equal or better than a lexan hobie rudder. Net you want the outer profile the same shape, I would run 3 layers of 1" wide uni carbon down the 1/4 chord and a minimum of 3 (structurally likely okay), better off with 6 layers of 9oz fiberglass on the bias around the blade. Assume 0.012" per layer and that should get you the core offset. You could cut the fiberglass down to 4 layers pretty safely if you replace the 9oz fiberglass with 5.7oz carbon, again you want most of the layers on the 45/45 bias.

The forecast for our area for Saturday in some wind data, i haven't found a good app yet that is right on yet! Wind seems very hard to predict, but they say at least 10 to 18 so we will see.

If i tried to build a rudder i might do it for fun at first to see if i can get the shape right, then i would just do fiberglass nothing like carbon stuff.. The biggest thing is to have a workshop area to play in, i have a garage but its a small one and things like build up in corners of the garage and things get moved around way to much! I need to organize things first that part sux! When i got this boat i had 6 guys help me move one hull in at a time in the winter so i could repair the blisters , I built 2 big Cradles with wheels, that took me til 4 months to finish it

These rudders don't seem to have any issues releasing popping up, but i started to pop them up anyways when i am coming in as i got close to hitting bottom, but all i have to say is what a improvement form what i had!

These were the old ones!Old rudder

old

I had the identical pair on my 83 TheMightyHobie18
they worked perfectly until (just like Damon stated) they didn't - they developed a crack (probably from soft beaching)
i then paid Hobie $800 for the upgrade kit (on my $400 catamaran)