Another Rudder Thread

[deisher6]

I recall a similar discussion on CP-16's.  The two biggest improvements for our '16 that I made were the Ida rudder and new sails.  I just happened to have the picture of the original and Ida rudder.  It certainly improved pointing, stalling,and weather helm.
regards
charlie

[Jim in TC]

It looks to me as though the benefits Eddie is citing come mostly from the rudder profile, not from a significant increase in size (a little larger, but apparently not much). Am I correct in that interpretation of the photos?

[Eddie C]

The foil has a little less overall area, is longer with less chord depth. Improved performance is noted at all speeds - steerage under power at idling speed is much improved. The NACA foil develops lift and carves its away through the water. The flat plate creates constant turbulence and steers by pushing the stern to the side. I took measurements at completion of the project but don?t have them handy. Adding the styrofoam and epoxy was an easy way to plug the ends. Drain holes sound reasonable to me. The Sun/Sundaycat is an excellent hull which is deserving of a much better rudder than the stock flat plate.
Eddie C

[bruce]

Eddie posted as I wrote this, but I'll send my 2 cents. If I hadn't foiled my rudder already, I would seriously consider the Windknife!

It looks like the Windknife sleeve, as installed, is a couple of inches forward from the stock position. You could trim both the leading and trailing edges of the stock rudder core and get it closer to the stock position, if desired. The cord of the sleeve, i.e. width, is  27 cm (10 9/16"), vs. 12" for the stock rudder as Roland reports, so he's lost a little in width, about 12%.

The sleeve is 110 cm long (43.3"), which in photo (last 4 digits) 0353 lines up closely with the distance between the pivot and bottom of the stock blade. I don't think he trimmed the sleeve in length, I'm sure he'll correct me if I'm wrong. He did cut a roughly 3" notch in the sleeve, and I'm guessing the distance from the pivot on the stock blade to the top of the cut he made in the stock blade to be a bout 12". So I estimate he's added about 9" to the blade length, about 21%. A higher aspect rudder, i.e. deeper, will definitely improve performance, at the cost of finding the bottom more often. Charlie definitely has a higher aspect over the stock blade on his CP 16.

Interestingly, the thickness of the sleeve is only 2.5 cm, or about 1 1/16". The maximum thickness of a NACA-0012 foil is, by definition, 15% of the cord, so for the sleeve, with a cord of 10 9/16" it should be 1.58", fully a 1/2" more. Flatter profiles are generally for higher speed, the NACA-0012 is a standard profile for rudders on boats like the SC.

I think both the higher aspect and the foil are contributing. Moving the blade forward, like the raking discussion we've had before, can lead to lee helm, but Eddie likes the feel of the rudder, so it may be he'd have more weather helm if the sleeve was closer to the stock position.

[Renae]

I hear fretting every time someone wants to put a stainless steel rivet in a dry boom.  Is there concern about an aluminum sleeve on a SS rudder below the waterline?

Edit:  Hey!  It's my 100th post.  I'm a centurion!

[bruce]

Congratulations on your hundredth!

There certainly would be a concern, but the stock rudder is 3/8" aluminum, I believe. The centerboard is SS.

[Reighnman]

These post are extremely helpful and makes me realize just how little I know and understand. Ruddercraft now makes a kick-up specifically for the suncat transom. The price difference between just blade replacement and full set-up is about $265. Will I regret being cheap. Also read drilling the hole on just the blade isn't a walk in the park.  I'm not handy enough to be sawing my stock blade and installing the windknife.

[bruce]

At $424 for the blade alone, and $689 for the full assembly, I think the latter is a better deal, if expensive. With just the blade, you still have the stock set up of an uphaul pendant and pivot tightening to hold the rudder down. Having to reach over the transom to tighten the pivot, or install a pin, is pretty crude IMHO. There are good solutions for that, but require some DIY. I like my rod system, and I think I've worked out a good downhaul, using bungee or line led to the tiller. Off-the-shelf options are limited.

Com-Pac does offer a rudder hold down bar. Some have reported issues getting it to work. Brackish has a fix that works well for him. I haven't had the pleasure to play with it.
https://cpyoa.com/forum/index.php?topic=8217.msg60790#msg60790
https://cpyoa.com/forum/index.php?topic=7267.msg53521#msg53521

Here's a few more links to check out. Rudder Craft suggested the third one, although it's for a Legacy installation, as descriptive of the process. Hopefully someone who's recently installed the fully assembly on their SC can say if they had problems. We know Bub had trouble with his blade only install. Hopefully they've taken his feedback to heart, or maybe it's business as usual.
https://cpyoa.com/forum/index.php?topic=3932.msg27318#msg27318
https://cpyoa.com/forum/index.php?topic=4695.msg32652#msg32652
https://forum.trailersailor.com/post.php?id=1471491

Have to question if any products described here are plug and play!

[Roland of Macatawa]

Bruce, Jim in TC:

I'm inclined to select the Ruddercraft blade only choice over their full assembly choice,
and deal with the complications of keeping the Com-Pac rudder head.
For two reasons:

1. The blade-only blade, using the Com-Pac rudder head, is positioned in a more balanced location, reducing helm force.

2. The Ruddercraft assembly raise/lower mechanism doesn't seem to work as well as advertised.
Asking Jim-in-TC to add his comment about this.
I've sailed with Jim twice. He finds it necessary to supplement the Ruddercraft pull-line with a boat-hook to push or pull the blade fully down or up.
My interpretation is the the pull-line mechanism doesn't pull the blade to top-dead-center of its rotation well enough for momentum to carry it over to the opposite end-of-travel position as the gas strut re-extends.
Or perhaps Jim's gas strut lacks sufficient pressure to overcome friction to push to the end-of-travel position.
But greater pressure might inhibit the kick-up feature of the assembly. So, keeping friction low seems essential.
Yet this up/down pull-line is claimed to be a major feature of the assembly design.

Recently P-sail, on this forum, offered his used SunCat Ruddercraft blade-only blade for sale,
because he has now purchased the full Ruddercraft assembly.
https://cpyoa.com/forum/index.php?topic=11963.0
Would be very interested in his comparison of the two once he puts the new one into service.

Regards, Roland

[bruce]

Roland,

Can't disagree with your conclusions. 

I tried to offer recommendations that fit his needs, tempered with a healthy dose of this may not be as easy as he'd hope. A lot of things could be done for $200-300 bucks, if you're handy, but Ryan doesn't appear to want a DIY project. Costing wise, they're asking too much for the blade only, IMHO.

Bottom line, I think the best advice is to sail the boat for a while and see if you think you need to make a change. The stock rudder, on the PC at least, isn't that bad.

[Jim in TC]

I certainly have been disappointed in the "kick-up" feature advertised. After a lot of serious practice on the hard I could not get the rudder to kick all the way back up. Whether it was from beating things up a bit (you are supposed to give the line a hard jerk to get it up) or some other factor, soon after I found that one of the pintles had come loose. By good fortune, these tuck into the housing (so still hold on to the rudder) and have a plastic sleeve that prevents it from dropping out (and of course sinking). A welding shop made quick work of the repair, but it let go again last season (requiring another trip to the welding shop).

Whether this whole issue is on account of age (mine or the rudder's - there is no date on the paperwork that remains, but I expect it was purchased no more than a year or two after the 2006 boat purchase by the PO) I can't say. I took some of it apart at one point and the gas strut "seems" robust but have no way to compare with new. Loosening over-tight hardware helped some (especially going down). All that said, I don't find using the hook to be a major problem.

I talked to a guy at Ruddercraft last week who suggested that they have a "Size B" blade that is 48" x 10 1/2" , which would exceed the length of the assembly suggested for the Sun (and the Compac stock rudder) by about 12". It is 1 1/2" thick - which would fit in our case. The PO had this custom made by Ida Rudder (Ruddercraft's previous iteration) so I am not at all sure this larger rudder will fit "stock" hardware. My notes are less clear than they should be, but I am pretty sure the blade only option is smaller than both the original and the Ruddercraft assembly.

[bruce]

Jim,

Looking back at your original post in this thread, you said another SC owner with a Ruddercraft rudder felt the rudder might be too small. Was he talking about his rudder, or yours, and did he have the blade only or the full system?

Size B, extending a foot deeper, would give you more bite, at significant expense. It also will weigh 20-25% more, so the retracting issue, at least, will be worse. The added weight will also cause the blade to want to hang more vertically, and not forward to the intended stop, which could be an issue (see below). Personally, I'd try to maximize what you have, before springing for a size B.

Looking back at your photos from 5/15/19, reply #42 (p. 3) to Bub's thread, you have a green line attached about 1/3 way up from the bottom. That doesn't seem to have any significant purchase to hold the rudder forward to the stop as you'd want here, so I guess it's just to hold the rudder up as its retracted. But, it's creating a huge amount of turbulence being dragged through the water, negating the benefit of the foil. I'd lose that. Lines to secure the rudder for travel can be temporary.
https://cpyoa.com/forum/index.php?topic=11263.30

The next thing I'd check is is the rudder being held down securely? If the rudder can trail back in the stream even a few degrees it can seriously effect the feel of the rudder. On my boat, if I've forgotten to tighten the rudder in the down position, at 3-4 kts it will pivot aft and up and the helm will be horribly mushy and imprecise. Any kick-up feature has to keep the rudder firmly down in normal conditions, and only come into play if you hit something.

Both of these suggestions could make a world of difference. As far as the deploy and retract system, if you're stumped, it might make sense to send it back to Ruddercraft in the off season and let them check it out. They'll be able to tell if the gas struts are OK and if the system works as designed. The cost for diagnostic time shouldn't be too bad, it wouldn't take them long. The system should function as advertised, without work arounds.

[DanM]

My SC came with the Ruddercraft full assembly. I'm happy with it but the lift-up mechanism is not great. I can't raise it past about 30 degrees above horizontal. I spoke to the company and they gave me the story about the two pulls, etc and lead me to believe the gas strut is OK. There was a thread about this here, maybe earlier this year. Several other SC owners reported the same thing. A couple of them tried what I was thinking of- a light line to act as final uphaul. In the end, at least two owners said they just wind up grabbing it with a boat hook. I think the geometry of the rudder just doesn't lend itself to being hauled up the way they make it, and the gas strut doesn't cut it. That said, I wouldn't say don't get it on the basis of that, just manage your expectations on this one issue.

[Jim in TC]

Bruce

Shortly after those pictures were taken I eliminated the extra line - based partly on some comments at the time (eg turbulence) and plain inelegance. Plus not offering any significant benefit. A separate line for travel (which now that we are in a seasonal slip is rare) and a boat hook for full raise (occasionally to keep algae growth down) has been just fine.

I didn't price the Size B rudder during our conversation and haven't found exactly what he was talking about on their website. Beyond cost, the issues you mention are worth consideration and I would need some further research in any event to make sure I could drop that one into my existing hardware. I am not convinced of the need, since sailing in the conditions during which the current rudder "fails" is pretty rare and can be mitigated with reefing, simply spilling some wind (hey, its not a race) or taking a different tack.

The issue of the blade travelling back a bit is indeed important, and mentioned also by Gerry at ComPac (" If the rudder blade is not completely down, even if kicked back an inch, that will load up the pressure on the helm.") I don't have reason to think ours is "riding" back but also haven't really looked over the transom to check it out when at speed. Something to put on the list for next season. And given the excess of trouble I had on that final sail of the season (more noticeable than ever before), it makes me wonder if at least that time it was not fully deployed.

As for the guy who came by commenting about the size - he said he was wondering about his and noticed that we had the same rudder, though I didn't really know at the time that a "blade only" differed in size from the full system and not sure how obvious it is to a casual glance (and so not really certain which he has). So this whole rudder journey is based at least in part on incomplete and possibly faulty information! But shoot, nothing else in regard to the sailboat is going on this time of year (in the North, anyway).

[bruce]

It's unfortunate that you can't get one more sail in to do some more diagnosis, and have the winter to work on any changes that looked promising. It seems that most of the complaints I've heard are about the rudder not coming up, or staying up, like it's suppose to. It's such an unusual system, I have no sense of how well the blade is held down normally, or how it could be modified if that was the issue.

The state pulled the floats at our ramps. When we first got our boat we launched in the spring before the floats were set out, but these days we're just too lazy.