Prepping a 7.9 for offshore

[bigkahuna]

Hi all, new to the group and the 7.9, but not new to sailing by any stretch of the imagination. I've recently relocated to the East coast (the Outer Banks of North Carolina specifically) and want a boat I can plunk around the protected sounds or take outside into the ocean. Because of the lack of deep water berths and sailing , a lifting keel boat will expand where and when I can go sailing. Enter the 7.9. I can keep it on a trailer, drive it down the highway, and enjoy sailing on a relatively small budget.

I don't plan on crossing any oceans (I've done that on my Express 37) but when the weather looks good, be able to make a run down the coast (12 - 48 hours) to the next harbor entrance or perhaps sail to the Keys, the Bahamas, or even Bermuda (probably a 5 day trip) if the boat and I am up to it.

So what would the 7.9? I took note that one 7.9 did the TransPac. I've done one and, although it can be a rough trip it's generally not. I did a run from Monterey to San Diego in a Soverel 33 and got more wind rounding Point Conception than we ever did during the TransPac. So here's my list of to dos so far:

1. Make a provision to pin the keel in place (probably a large stainless steel bolt).
2. Collision bulkhead forward.
3. Beef up and secure the forward and companionway hatches.
4. Do something about the rudder. This is one area I'm not sure what I will do. I like that the rudder can be kicked up for shoal water, but the pivot weakens the rudder (the fellows who did the TransPac had theirs fail). Been there, done that (ours failed during TransPac, too). I'm thinking of converting the rudder to a cassette (similar to Flying Tigers and others). Build the top frame out of stainless steel, build the rudders so they can be lifted or even swapped if on breaks. My only worry is that the original rudder is "semi balanced", so this new rudder might have a ton of weather helm. That would be no bueno. Ideas?
5. Probably a small dodger or pram hood to keep the spray out of the cabin while the hatch is open.

Other thoughts or ideas?

[bigkahuna]

(No way of editing a post?)

More things "to do":
5. Beef up the cabin port lights.
6. Big, manual bilge pump.
7. All the other ORC / TransPac requirements.

[Jim Kloss]

Having sailed my 7.9 in the Caribbean for a dozen years and having had (too many) close encounters with reefs and a broken rudder off a lee shore, I'd have some different suggestions.

I don't think you can pin the rudder down through it's box without creating a nasty leak. If you're really worried, wedge a 2x4 between the top of the board and the stainless steel keel lifting plate. Although I recall reading that the board will stay down even when pitch-poled.

Instead of a forward bulkhead, I'd build a crush box around the leading edge of the dagger board trunk. I've had repeated failures there when the top of the keel tries to rotate forward; I need to learn to avoid reefs.

My rudder failed just below the cheekplates and it had nothing to do with the pivot point. I added belts of glass cloth around that area on the replacement. I think everyone uses a pin of some sort to prevent rudder kick-up, some go as far as a second bolt strengthening the whole assembly. I think you're right that a cassette rudder would add too much weather helm.

And of course the 7.9 wasn't built to be a salt water boat so isolate as many stainless steel fasteners going into aluminium as you can.

Hope those ideas help, and I'm sure you'll get other suggestions. Enjoy the boat.

Jim Kloss
s/v Ambivalence
S2 7.9 #8

[bigkahuna]

I don't think you can pin the rudder down through it's box without creating a nasty leak. If you're really worried, wedge a 2x4 between the top of the board and the stainless steel keel lifting plate. Although I recall reading that the board will stay down even when pitch-poled.

As long as the hole for the pin is above the water line and sealing washers are used, no water should come in. I had a custom MORC race boat that was very similar to the 7.9, it's lifting daggerboard was almost identical. I used a big bolt to pin the keel / daggerboard in place without issue. My understanding is that the boat that did the Transpac did this as well.

I like your crush box idea, I'll put some thought into that. With all the abandoned shipping containers floating about, doesn't hurt to be extra cautious.

Besides the mast, where else does stainless steel come in contact with aluminum on the boat? Are the rudder cheeks aluminum?

[Jim Kloss]

Yes, rudder cheek plates are aluminium. New ones can be ordered from Stef on this site -- he's a great resource. I've replaced mine twice. I also
have gone to over-size stainless pintles, and I put a sacrificial zinc on the bottom one.

Jim

[bigkahuna]

Yes, rudder cheek plates are aluminium. New ones can be ordered from Stef on this site -- he's a great resource. I've replaced mine twice. I also
have gone to over-size stainless pintles, and I put a sacrificial zinc on the bottom one.

Jim

Not sure the zinc is doing your stainless any good. It would need to be bonded to the aluminum somehow. When stainless and aluminum are in contact in a salt water environment, it's the aluminum that galvanically corrodes.

I would think stainless steel or carbon fiber cheek plates would be one solution (again, I'm not worried about class rules).

[bigkahuna]

Then again, maybe not carbon fiber: https://www.corrosionpedia.com/galvanic ... ers/2/1556

[alanhsails]

On advice from the guys on ARturo the Aquaboy, who did the Pacific Cup, I built a rudder. I have a thread about it, down below. The thread has links to Sailing Anarchy and the Wooden Boat forum where I documented how I did it in gory detail. I built in about 12% balance.

I had two reasons for building this rudder.. 1.) I plan to sail the boat to Hawaii and 2.) the stock rudder, while it never loads up terribly, also is extremely NOT directionally stable. You can't let go of it for two seconds, or it will be hard over, and you round up. As a shorthander, I can't deal with that. So I built in LESS balance than the stock rudder. The rudder I build is also significantly skinnier than the G&S designed rudder, though still way, way thicker than say a J-24 rudder.

I concur about the big bolt through the daggerboard case.

[bigkahuna]

On advice from the guys on ARturo the Aquaboy, who did the Pacific Cup, I built a rudder. I have a thread about it, down below. The thread has links to Sailing Anarchy and the Wooden Boat forum where I documented how I did it in gory detail. I built in about 12% balance.

I had two reasons for building this rudder.. 1.) I plan to sail the boat to Hawaii and 2.) the stock rudder, while it never loads up terribly, also is extremely NOT directionally stable. You can't let go of it for two seconds, or it will be hard over, and you round up. As a shorthander, I can't deal with that. So I built in LESS balance than the stock rudder. The rudder I build is also significantly skinnier than the G&S designed rudder, though still way, way thicker than say a J-24 rudder.

I concur about the big bolt through the daggerboard case.

Thanks for the reply Alan. Although you forgot to include links to your thread(s) I managed to find them. Lots of great info shared there. I'd love to see how your rudder turned out.

Regarding your plans for "less balance", I have to say I'm a bit confused. I have a fair bit of single and double handed ocean sailing experience, and in my opinion a bit of weather helm is a good thing, especially when you're sailing single handed. Not so much that it become fatiguing (or that it puts undue strain on your autopilot) but enough that if you should fall over the side while steering the boat will naturally want to round up so you aren't dragged behind by your tether. Of course I always rig my tether so it's so short I can't possibly fall over the side, but I have had to hand steer when the conditions are just too extreme for the pilot to keep up and things can go wrong when you least expect it...

I've also had my experience with rudder failures during an ocean crossing (about 1200 miles from land) and also the emergency rudder failing (about 100 miles later), so knowing how to build a strong and efficient rudder is definitely something I want to spend more time with.

[alanhsails]

Good question....OK, so my experience with the boat has been 100% positive with the ONLY exception being that the rudder is not directionally stable. By this I mean that no matter what point of sail you're on, you simply cannot let go of the tiller or the tiller will IMMEDIATELY head for the leeward side of the boat and you will round up. When I singlehand, especially when coming about, there are times when I need to let go of the tiller for two seconds, either to move my butt around to the other side, or get a wrap around a winch...something like that. I don't need to be able to let go for a minute...just 2-3 seconds.

Can't.

Guys on this forum have told me to make sure that the rudder is pinned down between the rudder cheeks or it will develop weather helm....and it is. Guys on Sailing Anarchy who have S2 9.1's, also built with a very similar rudder hanging off the transom, have the exact same issue.

Now, I will say that the Class rudder almost never loads up, horribly. Sure, a big roundup with the chute up can load up the tiller, but come on.... So in this way, the rudder is great.

The Class rudder is incredibly thick, like 3 inches thick. It also has a very large amount of balance built into it. "Thick" is both good and bad...good in that flow tends to stay attached to a thicker rudder even at high angles of attack, and that's a good thing. It's bad in that all the extra surface creates some drag. Skinny appendages slip through the water easier than thick ones.

Now, Graham and Schlageter were darned good designers. On the other hand, things have changed since 1980. The guys on Arturo the Aquaboy told me to get a custom rudder as they busted the kick-up rudder about 400 miles out on their first Pac Cup. I've had current S2 7.9 skippers tell me that they've busted rudders, too. You know, I just REALLY don't want to break a rudder, 500 miles off the coast, yanno? That kind of messes up your whole day. So I started looking into replacement rudders.

Custom Composites, aka "Phils Foils" will build one for us. I asked them about a rudder which was exactly the same as the class rudder below the waterline, but "fixed". They came back with a $2200 price tag. Woof. I asked C.C. about a semi-elliptical rudder, vis a vis a contact I had with a guy on Sailing Anarchy. He has a Hotfoot 27, which has a transom hung rudder and also is a "big main, small foretriangle" boat. . Price was the same. I contacted Larry Tuttle at Waterrat. Larry is pretty local to me. He pitched roughly the same number. So I contacted Jim Betts, who o built the rudder for the Aturo Boyz. Again. OUCH. I have no doubt that these guys turn out a foil that is better than what I can make but two boat bills is a LOT for moi.

And that's why I decided to build my own.

[alanhsails]

Also...Rudder Craft makes rudder that are "in the ballpark" in terms of size. However, their rudder that was **allll-most** exactly what I thought I wanted is machined out of HDPE...and that stuff bends. They make a rudder which is a scooch smaller, out of wood core and fiberglass, and honestly that probably would have worked out fine. I just wanted something a **little** bit bigger.

I am not an engineer, nor am I a wizard at hydrodynamics. Because of this I decided that the smartest thing I could do is build a rudder with a constant chord, as I don't have access to a CAD cutter. I am more comfortable with wood than I am with foam-core carbon, so a douglas fir core, sheathed in 'glass was the way to go. I asked the whizkids on the Wooden Boat Forum and the Fixit Forum at Sailing Anarchy, a whole lot of questions, and wound up sheathing the thing in triaxial glass. I borrowed a vacuum pump, and bought all the "stuff" do do vacuum bagging on the rudder. I practiced on my emergency rudder, first before doing the primary rudder.

Shape.... Well, I knew that the rudder would be a constant chord rudder. I wanted it to be fat...not as fat as the Class rudder, but still pretty darned fat. Fat means strong, 'cause there's a lot of wood in there. Fat means the flow stays attached. My rudder will be about 1/3 skinnier than the Class rudder, so it's still going to be a little bit slipperier in the water. I wanted to retain as much attached flow as made sense, built a brutally strong rudder, and maybe trade off a little bit of balance for some directional stability.

I looked at a J-24 rudder. Damn, but those things are SKINNY. They're, like, an inch thick. What I wanted was more like a J-29 rudder. I know it's overkill, but the J-29 rudder has about the same surface area as the stock S2 7.9 rudder. The Class S2 7.9 rudder is MASSIVE for a 26 foot boat.

so how did I decide how much balance to give my rudder? I used the very scientific WASOTP approach. "Wild Ass Seat Of The Pants"...

[alanhsails]

This means that I went out on the Interwebb and looked up pictures of balanced rudders from as many designs as I could find in the 25-29 foot range. Here are a few.


Custom Composites rudder for a J-29 / J-30


Here's Rudder Crafts generic balanced rudder for any number of 25-27 foot boats




Sonata Rudder



You get the idea....I just eyeballed those, leaning heavily towards the CCI rudder for the J-29 / J-30 and I made it "like that". Turns out it's about 12% balanced. The actual pintle pins are about 3/4 of an inch behind the leading edge. If I hadn't cut back the stock, the leading edge of the rudder would be about 1/2 inch behind the pintle pins.

[alanhsails]

for how I built it, see the threads where I loaded up every freaking detail.

End Result? It works! I'm still messing with bushings, so there's play in the gudgeons/pintles, but the rudder works well. I have good control, PHRF Nor Cal didn't penalize me *Anything* for the new rudder (it's almost exactly the same underwater cross-sectional area as the class rudder) ...and I can let go of the tiller for a couple of seconds and the boat doesn't round up *instantly*.

I still have the class rudder for when the day comes that I sell it.

Also, I built the emergency rudder with a huge...like 20% cutback for balance. The e-rudder cassette is built to be the same fore-and-aft size as the underwater foil of the blade. The top of the rudder blade is almost 3 1/2 inches smaller, fore-and-aft than the underwater part. When the e-rudder goes in it's cassette, you push it down all the way. Then you jam a wood "spacer" in the back, between the back of the top part of the rudder, and the back of the cassette. That shoves the rudder forward in the cassette and voila, the e-rudder is now a semi-balanced rudder. There are some appropriately placed holes for some through-bolts to hold everything in place.

I still have to try this!

I hope this massive series of posts was helpful.

[alanhsails]

I am considering replacing the class "drop-in" pintles on the transom with some custom ones that will look a lot more like J -29 / J-30 gudgeons and pintles. The J's use a 1-inch pin, which is preposterous overkill for an S2 7.9. Stock on our rudder is a 5/8th pin if I remember correctly. NOBODY sells 5/8th inch rudder hardware. NOBODY.

I wish I could find out what the J-27 rudder setup is, but that information is nowhere to be found on the 'net, that I can see...and I looked A LOT.

[alanhsails]

1. Make a provision to pin the keel in place (probably a large stainless steel bolt). totally agree... maybe TWO bolts.

2. Collision bulkhead forward. I'd have to think about that. The only place to do that is to divide the V-berth... hmm.

3. Beef up and secure the forward and companionway hatches. I busted the lens out of my stock forward hatch last year, just by stepping on it, hard. I replaced it with thicker lexan and so far so good but I can sure see the logic of putting a nice Lewmar or Bomar hatch in there. I wouldn't replace it for local Bay sailing, or jaunts to the Farallones but I sure as hell would have an oversized piece of plywood available with a couple of holes in it for bolts, and then a piece of 2 x 2 also drilled for the bolts to hold the plywood down on the hatch opening. I'm going to build a hatch scabbard for the main companionway hatch before any really big offshore stuff.. This can be a couple of layers of laminated, bent doorskins, with some 6 oz 'glass in epoxy on top I think.


4. Do something about the rudder.......... Right!

5. Probably a small dodger or pram hood to keep the spray out of the cabin while the hatch is open. ... So much depends on your personal size, and how easy/difficult it is to get in and out of the companionway. I built a hard mini-dodger to cover the companionway of my Santana 3030, and it worked great but man it was a *project*. I built it out of foam sandwich...the pink stuff from Home Depot, between door skins. I cutout parts for windows, which were lexan. I have to see if the thing will fit on the S2. Honest truth is that I didn't really need it. When I did the SHTP on my Santa Cruz 27 I didn't have anything but a way to drape some thick, clear plastic over the companionway....worked fine, and the S2 7.9 is a drier boat than the Santa Cruz.