BayRaider vertical-hanging rudder

[Graham W]

The rudder of older BR20’s and BRe’s is attached to the angled transom, which cants the leading edge of the rudder quite far forward (photo below).  This can potentially give rise to significant weather helm, especially in strong winds. 

Newer versions of both boats now have a different configuration.  This involves a new moulding inset into the stern, allowing the rudder to be hung vertically.  Those who have sailed both versions say that it lightens the helm considerably and allows for much faster tacking.  And presumably if you’re not fighting weather helm, it also provides faster progress to windward.

Older boats can now undergo drastic surgery to the transom at the yard (described by one owner as ‘cut and shut’) at hefty cost, giving instant improvement to handling.  I think that when I win the lottery tonight, I’ll just buy a new model.  Plus a BC23 of course, which also has this vertical arrangement.

In the unlikely event that I fail to win the lottery, what would be the effect on the helm of preventing the old-style rudder from dropping beyond the vertical?  Using a wedge or something, so that the leading edge would no longer be canted forward.  I’m hoping that some clever engineer on here can say why this seemingly simple solution doesn’t work.

[Paul Beardsell]

Isn't the issue the area of the rudder fore and aft of the axis of rotation of the rudder, not the angle of the axis? It's the horizontal distance of the centre of effort of the rudder to its axis of rotation which says how much weather/lee helm you'll have. (oops, but see clarification below)

[Graham W]

Paul,

You’ll have to excuse my ignorance, but if the rudder is fixed straight down instead of being allowed to cant forward, doesn’t that place more of its area behind the axis of rotation, which I assume is the set of pintles attached to the transom? As I keep being overlooked by the lottery I’m trying to find a seriously cheapskate way of achieving some of the benefits of ‘cut and shut’.

[Paul Beardsell]

I'm very far from having any good relevant expertise when it comes to boat design and I was wrong to write: "It's the horizontal distance of the centre of effort of the rudder to its axis of rotation which says how much weather/lee helm you'll have." No, that dictates how hard must one must pull on the tiller to steer e.g. to correct for weather helm.

But given some weather helm is generally considered a good thing, that the tiller doesn't require a very strong pull to correct for it is also a good thing. If, on the other hand (so to speak), what is required is a better balanced boat, less weather helm, then that's where the centre of sail effort vs the centre of water resistance is important: sail balance, mizzen sail, main mast rake, etc. And reefing to prevent heeling as when heeling the centre of forward push of the sails is well off to the lee side pushing the bow to windward i.e. heeling causes significant extra weather helm. Swinging the keel aft a bit will reduce weather helm too.

I'm only recently back into sailing so I'm probably exhibiting the Dunning-Kruger effect, and teaching grandma etc etc, so excuse me. But I think when people talk about weather helm often people are talking about how hard must the pull be on the tiller to correct for it, rather than the oft-considered desirable tendency of the boat to weathercock into wind given e.g. a strong gust.

How hard one must pull on the tiller is not weather helm but rudder balance. And that is all to do with "the horizontal distance of the centre of effort of the rudder to its axis of rotation". Draw a line thru the rudder pins to find the axis of rotation. Adjust the rudder blade more forward of that line to reduce tiller effort. Adjusting that axis more vertical will have little effect on tiller effort. The primary adjustment to tiller effort is the position of the rudder blade relative the rudder axis, not the angle of the rudder axis relative the boat.

I think :-)

[Sea Simon]

I think PB, above, probably has the right basis. "Boat balance" (related to coe of ALL foils, above and below water) v "rudder balance"?

Perception of loads, "feedback", can also be an issue. I've regularly sailed a 1937 international 6m (sort of 40ft, mini J class style double ender) where anything more than the lightest touch of the tiller with one hand was an indication of something seriously wrong with sail trim.
Not necessarily a technical issue, in that these boats were built to be helmed by gentlemen who would not enjoy too much physical effort... they had chaps for that sort of thing!

The Supernova class had an issue, with a similar  configuration of transom hung, pivoted rudder. May be interesting?See
https://www.supernovadinghy.org/forum/viewtopic.php?f=2&t=979&sid=f9b1e8188e9c67cdf9606c15955124ca

GW. Your"modified stop" arrangement has to be worth a try,if only on a temporary/experimental basis?

You'd better get a yard slot booked ready for that lottery win. Regardless of cash, there seems to be increasing difficulties with supply of materials, and available men/machines ?
Last week's shortage here was steel rebar (nowt available) even ordinary timber is getting difficult at times.
 I was in a large agricultural merchant's this week...they had ONE yard broom in stock!

[Graham W]

Paul, Simon

Thank you, I now understand that I have been confusing two separate issues - weather helm and the effort that needs to be expended through the tiller to correct weather helm.  So it requires less force to steer when I have my flying jib hanging off the front because I’m on the cusp of lee helm.  Without the flying jib, I’m fighting increased weather helm more than I need to because of imperfectly placed rudder pintles.

So you should draw a line through the rudder pintles to find the axis of rotation and then move the rudder blade more forward of that line to reduce tiller effort.  With the old-style placement of the pintles, part of the rudder would need to be further forward than it is already, no doubt causing all sorts of other problems.  Crude diagrams below, showing current set up on old BayRaiders (1), new set up (2) and possible ways of modifying the rudder rather than the pintles (3 and 4), neither of which are very practical.

Is the problem with the old-style pintle arrangement not only associated with the placement of the rudder relative to its axis of rotation but also with what the rudder is doing when the boat is heeled, or is that an entirely separate issue?

For example, you’re on a starboard tack and the boat is heeled to port.  To counteract weather helm, you need to steer to port, pulling the tiller towards you as you sit on the starboard gunwale.  This pivots the rudder blade towards port, which not only alters the boat’s course towards port but also tries to lift the stern out of the water.  Is that lifting effect exacerbating the axis of rotation problem?  And the greater the boat’s heel, the worse the attempted lifting effect gets, which is a reason for keeping the boat flat?  Would the new pintle arrangement (2) also reduce the rudder’s attempt to lift the stern when heeled?  Those are probably GCSE-level geometry questions but I did latin at school, and not from choice.
 

[Paul Beardsell]

That's a very good point, Graham, which I had not considered. With a non-vertical rudder axis then depending on the forward/backward angle turning the rudder will also tend to bury or lift the stern, and this problem will be worsened when heeled.

[Ape Ears]

Graham,

Have you considered the effect of the 'wings' on the Bayraider rudder where the step is halfway up. Increasing the forward angle of the rudder is likely to increase drag, I doubt if it would increase lift like a winged keel ! Heeling the boat also compounds the forces on the rudder and lee/weather helm.

I think the geometry of the existing rudder is probably best suited to have the leading edge vertical and the 'wings' horizontal. The rudder blade on 'CraiC' is elliptical and can be tilted forward and back with very noticeable effect on the 'weight' of the helm and maintaining a neutral feel on a steady course with the rig balanced. I am still not quite sure where is best, and have used 'stops' on the stock to prevent the rudder tilting too far forward.

A forward angled rudder acts as a very effective weed collector , and also acts as a much better brake if impaled on a mud or sandbank as it is more reluctant to rotate and lift .
 

[Graham W]

Andrew,

I can imagine a forward-angled rudder bursting off its pintles if it contacted a sandbank.  And the existing rudder already has a passion for collecting bladder wrack without making things worse.

Winning the lottery it is, then.

[MarkDarley]

Graham,
When I bought "Pippin" (wooden Bayraider 20) she had the earlier forward hung rudder. As she needed considerable cosmetic work and all her hull fittings etc. were tired, when Matt suggested we cut the transom off and give her the new arrangement, I quickly agreed.  As far as I know she is the only wooden Bayraider 20 to have been retrofitted.  Two fingers on the helm in all conditions now.  I highly recommend the change.
I will let you know if I ever put her up for sale.  It probably won't be until after I have done another Sail Caledonia Raid with brothers and beaten Andrew in Craic, so don't hold your breathe!

[Graham W]

Mark,

When giving me the bad news on price, the yard told me that one wooden BR and one GRP BRe had been converted so far.  Now I know who both of you are and it’s good to know that both are very satisfied with the modification. 

I’ve never had a problem with quite fast tacking but I understand that the mod makes it even quicker.  If fighting weather helm is to do with the rudder’s problematic axis of rotation rather than with the weather helm being excessive, then is progress to windward any faster?  And a cruising question, does the mod’s lighter steering mean that it’s easier or harder to keep a hands-free fixed course relative to the wind using a tiller tamer? I managed to get it to work well on my heavy old style set up, out at sea and with a steady wind.

Once I’ve won the lottery (any day now) I’ll be able to start assembling a kettle of my own swallows.

[Sea Simon]

"For example, you’re on a starboard tack and the boat is heeled to port.  To counteract weather helm, you need to steer to port, pulling the tiller towards you as you sit on the starboard gunwale.  This pivots the rudder blade towards port, which not only alters the boat’s course towards port but also tries to lift the stern out of the water.  Is that lifting effect exacerbating the axis of rotation problem?  And the greater the boat’s heel, the worse the attempted lifting effect gets, which is a reason for keeping the boat flat?  Would the new pintle arrangement (2) also reduce the rudder’s attempt to lift the stern when heeled?  Those are probably GCSE-level geometry questions but I did latin at school, and not from choice."

Steve Cockerill of Rooster Sailing used to have a very good talk on this topic in his "boat whisperer" series of talks and videos. Using a Laser dinghy as an example.
I think youre right GW. The essence seemed to me to be...keep the boat flat!

Just did a quick search, but unable to find this video now.

Not sure if he still tours doing his Whisperer talks (covid aside, of course) but I've been to two of his events and they are excellent.
Good mid-winter fund raisers for any SC too!

[graham2burton65@gmail.com]

I am following this thread with great interest.

when I bought my BC20, one of the features I disliked was the rudder as discussed above.
I could find no reference to altering it so I sketched out a design idea that I propose to set in motion


attached should be three sketches.
one is a sketch of a stainless fabricated / bent bracket that should bolt to the existing pintle and gudgen bolt holes.  This bracket then provides the vertical orientation I am seeking.
I would need to alter the angle of the tiller and I propose to have made,  by Mat, a shallower balanced rudder blade i.e. with some blade in front of the vertical pivot line.

I would b very interested in your thoughts.

Another issue that I would like improved is the horizontal angle through which the tiller moves.  It seems to hit the cockpit seats before getting a decent angle.  I am planning to work on this...

[Llafurio]

Just for the record.: Since 2005, I never saw a problem with the forward tilted rudderblade of my Swallowboats. On the contrary, I love it, it makes the boat turn quicker. In one regatta in the Netherlands I -almost- crashed the boat because of friction in the rudderhead I could not get the rudderblade full down and forward, so the boat was sluggish going through the tacks at tacking up a narrow canal. -I will not modify my rudder for vertical hanging.

[Graham W]

The underwater photo below seems to show that my BR20’s rudder is canted forward, while the centreboard is perpendicular.   It might explain why my steering is not quite so heavy as has been reported by some others.

Presumably it would be possible to lighten the steering still further by canting the rudder even further forward.  This could be achieved by grinding it down by a small amount where the top of the rudder abuts the front of the stainless stock - the arrowed straight bit between the two pintles, as in the second photo.  Unlike major surgery on the transom, this modification would be easy to reverse with epoxy if it was found to be a step too far.