External rudder upgrade?

[bhm]

I've now test-sailed my new-to-me 1962 Super Sailfish twice, and experienced first-hand the drawbacks of the old-style rudder, including its tendency to pop loose unexpectedly when pulled far over. So now I am thinking about adapting the rudder mount to accept the new-style rudder that I already have on my 1973 Minifish. This would require some adjustments to the tiller extension, but I was going to have to do that anyway, due to the idiosyncratic way I am sailing these boats. That in turn is illustrated by the following picture, which however has nothing to do with my immediate question, and is included here only for a cheap laugh:

So, my actual question is this. Is it feasible to do a quick and dirty external rudder upgrade without cutting into the hull, just by attaching a wood block to the transom using the existing external rudder hardware, and then bolting the U-shaped new-style rudder bracket to that wood block? Especially, I'm thinking that it should be possible to mount the bronze fitting from the old rudder to the front-side of this block in such a way that the existing pin-plus-clamp assembly on the stern could hold it well enough against the transom (if fully clamped down, so that it would not pop up).

 

[Charles Howard]

Does your rudder bolt have the plastic tube?

 

[bhm]

No -- I've heard about that but did these first two trials without trying that, then jumped immediately to thinking about switching to the new rudder.

Edit: on reflection I suppose that before taking the old rudder apart to use the parts for a remount like this, I should at least try clamping the wing nut all the way down, to totally disable the pop-up feature of the old rudder.

 

[signal charlie]

Check the bottom tip of the vertical hinge for wear, as well as the cup on the keel latch plate. And look at the spring plate on the deck, is it straight? Worn or bent components will not hold properly,

 

[beldar boathead]

Clamping the wing nut all the way down does not solve the pop up problem. You need the plastic tube to solve the problem. The problem is the carriage bolt and plate on the bottom of the boat wiggle from side to side without the tube, allowing the rudder to pop up. Fortunately the tube is cheaper and easier than a rudder conversion.

 

[bhm]

Check the bottom tip of the vertical hinge for wear, as well as the cup on the keel latch plate. And look at the spring plate on the deck, is it straight? Worn or bent components will not hold properly,

Are these the parts you mean? (I don't know their proper names.)

When I posted these pictures in a previous thread, you said, "The leaf spring on top of the horizontal hinge plate seems straight, and the beveled edges on the vertical hinge plate attached to the rudder blade and beveled edge on the keel latch plate do not look worn. Those areas are where undesired rudder releasing originate. Depending on your launching, sailing and beaching conditions and preferences, you'll find a "Goldilocks" thumbscrew setting for your rudder assembly, too much and the rudder is hard to latch and unlatch, too little and the bottom pops loose under sail. You can still sail if it releases, but not with as much control. "

If these parts aren't worn, it seems most likely that I just haven't tightened the wing-nut far enough yet. My first test-sail (on a small flat lake where I try out new boats and rigs) was with the 45 SF Snark sail and it did not pop loose. Today I used the 65 SF Minifish sail with the same setting and it did pop loose, twice. So evidently I should at least tighten the wing-nut more, and also try some tubing over that vertical bolt.

 

[bhm]

Clamping the wing nut all the way down does not solve the pop up problem. You need the plastic tube to solve the problem. The problem is the carriage bolt and plate on the bottom of the boat wiggle from side to side without the tube, allowing the rudder to pop up. Fortunately the tube is cheaper and easier than a rudder conversion.

What are the preferred mechanical properties of this tubing to sleeve over the vertical bolt? Does it need to be soft and flexible, like nylon or rubber tubing, or can it be hard plastic, like a ball-point pen barrel?

 

[bhm]

Clamping the wing nut all the way down does not solve the pop up problem. You need the plastic tube to solve the problem. The problem is the carriage bolt and plate on the bottom of the boat wiggle from side to side without the tube, allowing the rudder to pop up. Fortunately the tube is cheaper and easier than a rudder conversion.

I think now I understand. The idea is to reduce the side-to-side play in the vertical bolt, by sleeving anything over it that will fit over the 1/4 inch vertical carriage bolt but still fit into the groove in the fiberglass transom? I.e. something like this?

This is 11 mm outer diameter hard black plastic over a Bic pen barrel:

I could probably get a tighter fit by wrapping some Gorilla tape around the outside of that. But if this is what you are talking about, could this be a sufficient fix already?

 

[Sailflow]

Try to get some closer to the real tube.

From the forum
The tube I used measures 1/4" ID x 1/2" OD x 5 1/4"+. I know that I bought a one foot length, as I have the surplus on the desk in front of me.

So looking at the McMaster catalogue, and knowing what I would be looking for, I probably bought "Chemical-Resistant Slippery PTFE Tubes"
and not the nylon tube, as I originally stated. The tube I have is white, while the nylon tube is more clear. Have a look at the attached which shows the leftover piece along with an NOS nylon tube and carriage bolt that I picked up later.

The tube does feel slippery. Also, the McMaster catalogue says for "Use Outdoors" and since that where Sunfish live, I likely would have factored that into the decision. Finally, I would have opted for the one foot section over the 5 foot section even though the unit cost is higher. What in the world do you do with an extra 4.5+ feet of tubing? The extra tubing I have has sat in a drawer for the last four years, and will almost certainly be sitting there in another four. Looking at the piece of PFTE I put on the boat four years ago, it looks practically new.

Regardless, I don't think it much matters much whether nylon or PFTE, but I would go with the PTFE as the carriage bolt fits more tightly. The whole purpose of the thing is to resist lateral motion, so the tighter the fit, within reason of course, the better.

The exact number in McMaster for the PTFE tube is 8547K31. A one foot piece is listed at $5.94 plus shipping.

If you or anyone else wants nylon, the number is 8628K27. You do have to buy a five feet however which costs $12.20 plus shipping.

Hope that is helpful.

Attachments

• 
  IMG_5147.JPG

 

[bhm]

Try to get some closer to the real tube.

From the forum
The tube I used measures 1/4" ID x 1/2" OD x 5 1/4"+. I know that I bought a one foot length, as I have the surplus on the desk in front of me.

So looking at the McMaster catalogue, and knowing what I would be looking for, I probably bought "Chemical-Resistant Slippery PTFE Tubes"
and not the nylon tube, as I originally stated. The tube I have is white, while the nylon tube is more clear. Have a look at the attached which shows the leftover piece along with an NOS nylon tube and carriage bolt that I picked up later.

The tube does feel slippery. Also, the McMaster catalogue says for "Use Outdoors" and since that where Sunfish live, I likely would have factored that into the decision. Finally, I would have opted for the one foot section over the 5 foot section even though the unit cost is higher. What in the world do you do with an extra 4.5+ feet of tubing? The extra tubing I have has sat in a drawer for the last four years, and will almost certainly be sitting there in another four. Looking at the piece of PFTE I put on the boat four years ago, it looks practically new.

Regardless, I don't think it much matters much whether nylon or PFTE, but I would go with the PTFE as the carriage bolt fits more tightly. The whole purpose of the thing is to resist lateral motion, so the tighter the fit, within reason of course, the better.

The exact number in McMaster for the PTFE tube is 8547K31. A one foot piece is listed at $5.94 plus shipping.

If you or anyone else wants nylon, the number is 8628K27. You do have to buy a five feet however which costs $12.20 plus shipping.

Hope that is helpful.

Attachments

• 
  IMG_5147.JPG

Thanks for the very precise information. I just ordered the PTFE. I'm surprised that 1/2 inch OD fits into that groove, but I suppose it must if you have it on your boat. I suppose it must deform somewhat and wedge in very tightly, which as you say is evidently the point.

 

[Breeze Bender]

Here’s the tube. I had to increase the hole diameter with a drill bit to fit the vertical bolt through. You want a snug fit.

 

[bhm]

Here’s the tube. I had to increase the hole diameter with a drill bit to fit the vertical bolt through. You want a snug fit.

Received and installed today. (The only shipping option McMaster offered me was UPS, $10.15, but in this case that included overnight delivery!)

I too had to drill it out to its supposed ID of 1/4 inch.

Thanks again.

 

[beldar boathead]

Just make sure the tube is short enough to allow the carriage bolt to be tightened fairly tight. I don't believe the tube needs to be the max possible length - its purpose is to prevent the bolt from moving side to side.

 

[bhm]

Just make sure the tube is short enough to allow the carriage bolt to be tightened fairly tight. I don't believe the tube needs to be the max possible length - its purpose is to prevent the bolt from moving side to side.

Yes, I did confirm that, since I still somewhat distrust this clunky-seeming mechanism, and so I think I will want to cinch it down pretty tightly.

One odd thing I noticed is that for all settings of the wing nut, it snaps out much more easily than it snaps in. So if I did find a setting where it would take a good whack to knock it out, it will be impossible to just snap it in at that setting. So it seems like I am going to have to mess with that wing nut every time I mount this rudder anyway, so right now I'm thinking that I might as well just cinch it down pretty tightly, and take my chances on hitting something. I don't sail that fast anyway -- my top speed so far is only 5.5 mph, and I have no desire to go any faster than that.