Rudder Sizes for a 31 Bertram

Pete Fallon · Post by **Pete Fallon** » Apr 3rd, '12, 12:42

To the faithful,
A while ago there was a post about the difference in size on the 31 rudders. The 28' style was used quite a bit by the manufacturer, they are almost useless at low speed and with one engine forget about it. The 28 stlye were 12" long by 6" wide and had a 1-1/4" shaft, Patricks rudders are a major improvement, with a larger blade surface, see his post on rudders in the parts list.
On my 1961 31 Express I have 19" long by 9" at the top tappering to 7-1/2" at the bottom with 1" rudder post shafting. As far as I know these were the original rudders, I've had the boat for almost 35 years and it was in dry storage for 13 years before I got it. I never had a problem with steering at low speeds, and a few times I had to get home on one engine from 20 miles out, a long slow ride but no tracking problems. I think they found that my style were too expensive even back in the early 60's, I 've only see the old big ones on one other 31 after surveying over 30 of these vessels.
All I can add is if youv'e got the small rudders, they will work but you will have what we called snake wake at low speeds and sore arms after trying to correct your course for a long way offshore in a following sea. So my recommendation is to get Capt. Patricks oversized rudders and help him out.

Wursty · Post by **Wursty** » Apr 3rd, '12, 13:54

Order a pair from Capt. Patrick this past winter and are installed. They appear to be about 35% larger than the originals. Can't comment on the steering improvement yet since boat is in the NE coast and not launched yet. I'm anxious to experience the difference trolling using only 1 engine. With the old rudders I needed to be hardover to keep the boat straight on 1 motor. Apparently it's one of the better improvements ...

Charlie J · Post by **Charlie J** » Apr 3rd, '12, 14:09

wursty
you will be very happy with them

Wursty · Post by **Wursty** » Apr 3rd, '12, 14:17

I'll let the sandbox know next week once the boat gets splashed for 2012 season. I look forward to the improved steering preformance.

In Memory Walter K · Post by **In Memory Walter K** » Apr 3rd, '12, 14:40

I have a 64. My rudders have a straight forward side and a rounded stern side that is wider than the straight sided ones I have seen on other B-31's. I always troll for Bass on one engine with no problem. Coming in from offshore on one engine is doable as long as I keep it slow. No question, more rudder area makes for easier steering. Didn't realize what I have is so rare.

In Memory of Vicroy · Post by **In Memory of Vicroy** » Apr 3rd, '12, 16:20

My 1972 B31 came with B28 rudders and one engine operation was impossible without dragging a bucket off one side. I was one of the first to go with Patrick's oversize rudders and was able to eliminate a lot of the "toe in" which gave me some extra cruise speed. I can now run either Cummins 250 wide open and keep her straight with some helm to spare. And the autopilot loves 'em. The best improvment to a B31, period.

UV

Pete Fallon · Post by **Pete Fallon** » Apr 3rd, '12, 23:05

Walter,
Your rudders sound like the ones I posted about earlier, they have a forward edge about 3/4" to 1" thick and then a slight tapper aft, the larger rudders seem to be on the early 31's, they are made of cast bronze. Wursty, you will love the oversized rudders from Capt Pat.

Rawleigh · Post by **Rawleigh** » Apr 4th, '12, 08:59

My '66 came with the bigger rudders. Shaped sort of like a rounded shark fin.

In Memory Walter K · Post by **In Memory Walter K** » Apr 4th, '12, 09:25

Those are the ones.

bob lico · Post by **bob lico** » Apr 14th, '12, 22:59

after i gave them the nod. harry babb and dug put phoenix into a lock to lock turn to port into 2 to 3' waves at 34knt. other then a piece of chine at the stern the only thing holding that boat were those monster rudders. i think they will remember that for a long time at greenport .

Harry Babb · Post by **Harry Babb** » Apr 15th, '12, 11:00

I think about that ride a lot Bob.

The ole girl sure handles well.......good job! !

hb

Wursty · Post by **Wursty** » Apr 16th, '12, 07:51

Did the shake down yesterday with the newly installed Capt Pat's rudders.
Extremely satisfied at all speeds from 4 knots to 30 knots. Performance exactly as you all said even when only operating on one engine I can actually STEER the boat down the channel. Nice to have those oversized ruddders behind large props driven by 330HP 6BTA's. Thanks Capt Pat for making the rudders and thanks to the sandbox for encouraging me to make the improvement.

bob lico · Post by **bob lico** » Apr 16th, '12, 08:57

Wow 4knt. - Damn cannot do that on one engine into the wind with two 5 gallon buckets out the stern ! Miinimum speed at best 6knts.this winter I rip up the cockpit sole and the gears are apart because the pump had to come out with transmission end cap in one piece .the threaded set screws are frozen in gear case that allows you to take out just end cap. When installing trolling valves.You will also see a beneficial advantage coming in a inlet with 12' seas behind you .the boat can cut to port and starboard as to stay 45degrees to the waves under the boat along with varying speed you will build confidence going into a impossible inlet conditions it is all about the rudders.

Wursty · Post by **Wursty** » Apr 16th, '12, 09:28

Bob, I have trolling valves on my ZF's so can get very slow. However with both in gear w/o using valves I idle at 5.5 knots. Top end is 33 knots.
I look forward to steering through various sea conditions but for yesterdays shake down all went perfectly in flat water.

bertram31.com

Rudder Sizes for a 31 Bertram

Rudder Sizes for a 31 Bertram

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