Senta II rudder upgrade ?

[Sven]

I just got an answer back from Paul at Foss regarding upgrading Senta's rudder to bigger than IOR specs.

He suggested either using Bruce King's modification or a considerably higher aspect ratio rudder that they have installed before on other boats. BK's modified rudder has a larger surface area than the Foss alternative (8+ sq. ft vs 7+ sq. ft). The higher aspect ratio of the Foss alternative looks as if it would still be more effective than the BK redesign despite it's smaller surface area and it would also be further down in the propwash for control under power.

The higher aspect ratio looks less substantial than the BK design and I wonder if that should be a consideration for our planned off-shore use ?

Thoughts and opinions are most welcome.

Thanks,


-Sven

 

[Seth]

Another idea

HI Sven,

Hope all is well. First-there are no IOR specs for rudders-this was simply BK's rudder design, and while the overall boat design certainly took the IOR into account, there aren't any specific aspects of the rudder which conform or take advantage of the Rule. In fact, while the boat was designed to take IOR ratings into account-it was certainly not a boat designed strictly to the rule (or it would have been much more extreme-you should see the custom IOR BK designs like Terrorist, Hawkeye, and Aggressive II!). The design brief was for an all around Racer/Cruiser type which rated reasonably well under IOR, but not a true IOR boat.

Foss can hook you up with one alternative, but if you want to maximize your improvment at the lowest cost- do what Jim McCone did and go see Dennis Choate at Dencho Marine in the Long Beach area.

Just tell him you want a bigger better rudder and let him do his thing. Don't push him for etals-just trust him. It will be cheap and good.

Jim got out for about $1500 I think-not bad.

Check the threads for all of the other details about this, and good luck!

S

 

[Martin King]

That original mod is out of date. On my old 39, we extended the length
6"-nearly the length shown on the high aspect version, but with more
blade area down low. You might want to investigate this option as well.
Assuming you are keeping the old bushings, you would be well served
to mike them and have the new shaft turned accordingly.

 

[Guy Stevens]

The rudder in the photos from foss will not steer the boat

The rudder from Foss will not steer an e-39 at all at normal speeds. This has been pointed out to them from everyone that has gotten one from them. They still sell it even with at least 4 reports that I know they have gotten.

Backing becomes impossible and slow steering is non functional. I have sailed and motored on two of the boats that have these installed, they are less in area, and although have a "better" shape, they simply don't have the area to function.

Bruce redesigned the rudder with a lot more area. Owners who have upgraded their rudders per the design have found the Bruce King redesign makes a world of difference.

The other thing to take into account is that for most of the sailing that people are going to be doing in these boats, the standard rudder is sufficient, although the increase in control while backing the boat with the rudder mod is worth the work all by itself in my opinion. Carrying the spinnaker in higher winds without rounding up is good if you are racing too.

The Bruce King's first redesign adds about 27% to the area of the rudder. Extending it even more to 6 inches deeper rather than the 3 or so on the redesign would be even better.

The Foss redesign cuts the rudder area by about 12%, it simply does not steer the boat at anything less than hull speed.

Gary on Traveler has even more horror stories in dealing with Foss over this issue. He is on here occasionally now that he is out cruising.

Don't use Foss, DIY, or have a local yard do it....

Guy

 

[ChrisS]

Safe to modify the old one?

This is an interesting thread. Back when I was considering purchasing my 32-2, I read every rudder thread on this site, as well as on Sailnet, knowing that once day I might consider trying to tackle some improvement in this area.

Now, several years later, I am there. This past summer I sailed from SF to Catalina and back, and I am thinking of spending this coming summer in the Channel Islands. Even though my boat is over 35 years old, she did great in all areas of the six week trip (the only real failure was cracking the A-4's exhaust manifold while pounding up the Big Sur coast), and many times people approached me to talk about old Ericsons they had, and what great boats they are.

My only real complaint is going downwind, she feels a bit hard to control--so much so that I don't fly the chute in bigger winds that I would have done in my old Ranger 23 without a second thought. I know that part of this is due to hull design, but I wonder how much of it is determined by rudder size and shape. I also think about how long a 35 year old rudder will last before corrosion takes its toll--this summer, my first attempt to round Point Conception didn't go so well, and when I turned back downwind to go back to Cojo, I had to steer with every bit of concentration and precision I could muster, and I thought about what my fate would be if the rudder failed.

Sven, I don't mean to hijack your thread, but some of the Sailnet threads I came across spoke poorly of Foss, and so I wonder about Jim McCone's modification experience--from what I see he had his old rudder altered--how can you tell if a rudder can be rebuilt?

Thanks to Seth, Martin, and Guy for sharing their wisdom.

 

[tenders]

I'm watching this with interest too. The rudder on my '69 32 is cracked and leaky. I've ground out everything that looked bad down, and well into, the foam and am in the process of layering back up again. The local repair guy told me polyester was better than epoxy for this kind of repair, and I'm starting to doubt that too. I figure I probably have another gallon of polyester resin to go, but am a little doubtful that the result will be sufficiently sound.

I'm in the Northeast. How does one even GET a rudder to Foss (Florida) or Dencho (SoCal)?

 

[Martin King]

Actually Finco fabrication is located in Santa Ana, CA. I think they
are affiliated somehow with Foss. http://fincofab.com/

If you need to transport the rudder, you could always crate and ship it.

The local repair guy told me polyester was better than epoxy for this kind of repair

That's a good one. FYI-epoxy is stronger in secondary bonding applications.
Epoxy is also much better in resisting osmosis than polyester.

Anybody doing these types of repairs would be well advised to check out the Gougeon Bros. website
http://gougeon.com/

 

[Seth]

Rudder Stuff

I know Dencho can just take your old rudder and re-work it. If the metal needs to be repaired he can do that. Here is the info:
Dencho Marine, Inc
1517 W. 15th Street
Long Beach, CA 90813
(562) 432-3487
Toll Free- (888) 460-7395

info@denchomarine.com

Finco Fabricators is also good-as Martin suggests. Steve Brown there is an old buddy of mine. Last time I spoke with him he had a bunch of tooling for most of the E-boats, (stock Foss types), but I am pretty sure he can modify one as well. You can give him a design to build to, or you can just ask him to make it happen-he knows what he is doing. You will have to confirm they can do custom work, but I think they do.

For sure Choate (Dencho) can and will. Same thing there-you can give him drawings or let him work his magic-that is what I would do..

Later,
S

 

[Sven]

Thanks for all the feedback. Very good info.


-Sven

 

[Sven]

Hi Martin,

You and Guy and Seth ... etc. have talked me out of the original path I was following and I appreciate that redirection.

Assuming you are keeping the old bushings, you would be well served to mike them and have the new shaft turned accordingly.

Was that a typo or is "to mike them" a technical term that I'm not familiar with ?

Did you drop the rudder while in the water or did you haul out ? I'm assuming it weighs a ton but wonder if it floats or sinks (probably the latter) ?



-Sven

 

[tenders]

Oooh! Oooh! I know this one. "Miking" means "measure using a micrometer" or other precise tool to make sure the clearances are within tolerance.

 

[Sven]

Oooh! Oooh! I know this one. "Miking" means "measure using a micrometer" or other precise tool to make sure the clearances are within tolerance.

Ahhhhhh, that even makes sense

Thanks,



-Sven

 

[HughHarv]

Hi Martin,

You and Guy and Seth ... etc. have talked me out of the original path I was following and I appreciate that redirection.



Was that a typo or is "to mike them" a technical term that I'm not familiar with ?

Did you drop the rudder while in the water or did you haul out ? I'm assuming it weighs a ton but wonder if it floats or sinks (probably the latter) ?



-Sven

Sven, you probably have to drop the rudder out while on the hard as the lower gudgeon (for lack of better term) is below the waterlne and the three bolts attaching the gudgeon go through the hull. Don't think you'd want to rely on a temporary plug (aka: like fingers in the dike) for the time it takes to rebuild a rudder. I have my dry rudder out and, although it's cumbersome and bulky, I can pick it up and walk with it. If it was still full of water it would probably take a few more people to move it around. I'm extending mine several inches and adding a couple to the trailing edge referencing BK specs.

 

[Martin King]

Was that a typo or is "to mike them" a technical term that I'm not familiar with ?

Did you drop the rudder while in the water or did you haul out ? I'm assuming it weighs a ton but wonder if it floats or sinks (probably the latter) ?

Tenders pinpointed it for you. Generally what is done is the i.d. of the
bearings are miked in several places and the readings averaged. Make
sure the new shaft (you are doing a new one, right?) is turned on a
lathe so the shape is perfectly round and clearanced for your bearings.

I would never attempt dropping a 39 rudder in the water. The boat should
be hauled out. There are 3 throughbolts that hold on the gudgeon that
need to be removed. Depending on the bedding or lack thereof, it
may just slide out, or need some persuading. In any case, arrange
for blocking under the rudder, and have a couple of helpers standing
by to grab it and ease it out.