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Mark Weeks  
#1 Posted : 14 July 2017 14:50:02(UTC)
Rank: Member

Posts: 23

I have been playing with ideas on how to manage shoal water with my P27 rudder. As you will all know from experience using a half raised rudder is no joke especially if the wind is blowing and there is a chop.
I, for my sins, have a mooring which readily dries and therefore I am always looking for ways to get on and off safely with minimal water.

What has recently come to my attention that the rudder on the P27 is much longer and narrower than that of the Super Seal 26 or that of the P275, the Super Seal sharing an identical hull to the P27. Does anyone know why the Baker/Parker changed the rudder design on the 27 and then regressed to a similar design to the Super Seal Rudders for the Parker 275. At the recent Timbrells/Palace Quay rally the variance was noted when all three marks of boat happened to be mored alongside one other. Measurements taken locally show that although the P27 transom and tiller to pivot bolt lengths are slightly longer on the P27 in respect to the Super Seal (by about 4cm) the rudder blade is 17cm longer on the P27. That's nearly 7 inches longer which means an extra 30mins plus to get onto my mooring with full rudder.
The question is though, would a Super seal rudder fit a P27 stock and if so would it be as effective?
Any thoughts would be appreciated.
Another aspect of the long rudder is that when moored to a pontoon if the rudder is stowed raised it must not be allowed to sit towards the pontoon as in this position it extends beyond the boat over the pontoon with the inherent danger it causing an obstruction in the lease or in the worst , sustaining damage by hitting the pontoon should the boat be rolled towards the pontoon by the sea/wind/people. This is much less likely with the Super Seals shorter rudder which when raised does not extend beyond the beam of the boat.
Martin Watson  
#2 Posted : 14 July 2017 16:14:05(UTC)
Rank: Advanced Member

Posts: 40
Location: nr. Billingshurst, West Sussex

Hi Mark, from information I have received, it seems that not all P27s have longer rudder blades. Those that do, are fitted with the rudder blade from P31s, presumably to help with handling, as a longer blade is going to be more efficient ( you will notice that your rudder has a narrower chord as well). Various owners of Superseals and P27s have fitted auxiliary rudders, comprising of either cassette type blades that slide up and down the side of the rudder stock, or swiveling on the outside of the rudder stock and using the same pivot bolt. I have been toying with the idea of replacing my complete rudder assembly with a cassette style rudder which could be part lowered when in shoal waters. to regain the balanced rudder effect, it would have an angled cutaway on the rear of the top part and a wedge of the same dimension as the cutaway would be inserted in front of the blade top in the cassette stock, once the rudder was lowered fully. To prevent damage if the rudder were to strike some underwater object, I would propose some form of sliding hinge at the back of the rudder stock, held in place by several strands of powerful bungee cord that would allow the rudder to swing back in the event of contact with a submerged object. I'm still working out the details.
Martin Watson
Mark Weeks  
#3 Posted : 17 July 2017 12:22:11(UTC)
Rank: Member

Posts: 23

Martin,
Thanks for the info. Very interesting.
I have also toyed (and am still doing so) with various solutions to the problem, keeping things as simple as possible. I don't want to go away from the current rudder shape if at all possible, so I am considering a sliding stock. I have found by trial that if the rudder is pivoted to just clear the transom the load is not too large. If the whole stock could then slide vertically on a long pin between newly made, single plate transom mounts, the whole stock could slide vertically a foot or so, thus reducing the draft of the rudder from 1m+ to 0.6m ish. The design would have to have a measured stop of time type, if only a mark on the uphaul to stop the rudder rotating and then an up haul or down haul (dependant on whether the stock and rudder are buoyant or not) to raise the whole assembly up by up to 0.6m. This would mean that the tiller was now about 0.6m higher in the cockpit, but for manoeuvring in shallow water as relatively slow speeds this would not be a problem. An additional fitting on the stock would be required mid way between the normal 2 fitting to take the load when the upper fitting leaved the pintle.
The problem I have with using a secondary cassette type rudder is that the main rudder has to be pulled fully up and this creates not only an extra obstruction to be considered if near a dock but having the rudder fully up makes the tiller heavy and very unbalanced.
Other ideas I've considered are of a sliding cassette with the rudder still able to rotate once down. Also a cassette type using a curved leading edge on a roller to allow the rudder to be balanced once fully down. This requires some knowledge I don't currently have in hydrodynamics.
One day one of us will come up with the solution. Until then I guess we will all just keep muddling through.
Martin Gray  
#4 Posted : 19 July 2017 14:52:05(UTC)
Rank: Member

Posts: 11
Location: Rochester

Martin,
I have a long rudder and for shallow water I have a cassette attached to the rudder stock that houses a narrow blade. Although it is only infrequently used I find it quite adequate when in shallow water. With the rudder fully raised I have not found the weight on the tiller to be excessive. I have balanced the rig and the angle of the rudder to make Ariel light and steady on the helm with the result that I do not really need the deeper rudder blade. It may be that shortening the rudder and installing a cassette mounted secondary rudder would provide a simple and inexpensive solution.
regards
Martin Gray
Mark Weeks  
#5 Posted : 21 July 2017 08:46:11(UTC)
Rank: Member

Posts: 23

Martin Gray,
Thanks for the info. Do you have and details of your adaptation., or was it previously posted on the website?
Martin Gray  
#6 Posted : 21 July 2017 13:43:45(UTC)
Rank: Member

Posts: 11
Location: Rochester

7Hi Mark,
If you let me have your email I can take some pictures and send them on to you.
Regards
Martin



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