R25 Seaworthyness

[trailertrawlerkismet]

As far as a larger rudder I have a few thoughts as it relates to a prior fast trawler we had. We thought this boats rudder could have been larger based on trawler speed travel with a following sea.....we could be pushed around rather easily. In addition we thought a larger rudder would have helped the boats maneuverability in dockage situations. This was a single screw, semi-displacement trawler that could travel fast, like our Ranger Tugs....we mostly cruised at trawler speed. So when we asked the factory we were told that their naval engineer advised against a larger rudder because (even thou the boat would handle better at slow trawler speeds and while docking) a larger rudder would make steerage to sensitive and therefore sloppy at higher speeds. A friend of mine did install a larger rudder on the same make boat and the boats handling characteristics were much better at trawler speeds, in a following sea and docking. At higher speeds I personally did not think the sensitivity was that much different. I would think a larger rudder on our RT would act much the same however
it would be interesting to hear what thoughts John, Jeff or Andrew have on this subject. From a personal standpoint I think our R27 handles just fine and certainly better then our prior boat, a Fathom 40......could it be better, probably but at what expense vs return?

Jim

 

[knotflying]

Good points Jim. I am not a boat engineer, but It makes sense. A boat rudder has the same characteristics as a plane rudder or aileron. You will notice that if you add speed you get more authority over the rudder. This is why I found when docking and maneuvering at slow speed short bursts of power give you better steering. A larger rudder will give you better authority at slow speed and will be much more sensitive at higher speeds. I wouldn’t want to destroy the balance between the two by adding a larger rudder. It would be great to get a bit of feedback from the Ranger folks and their opinion. I also wonder how the autopilot will work with the larger rudder and if there needs to be an adjustment to it to compensate for the larger rudder.

 

[baz]

My dock buddy has bolted a large piece of aluminum plate to his R-25's rudder as he was convinced this would help with the low speed maneuverability and docking task. He doubled the surface area of the rudder in this way. I suggested that he might find the rudder too sensitive at high speeds... and he agreed but wanted to test things out. He seemed to know what he was talking about and had lots of seaman experience... he was 92 years old. I actually posted this encounter with the bolt on rudder plate about a year ago. I do believe he discussed this rudder modification with Andrew and my buddy said Andrew made little to no comment... :lol:

However, only last week I saw his R-25 in the dry dock and he was sawing off a large piece of the aluminum plate on the rudder. I stopped and asked him what he was up to. 😉 He admitted that the doubling of the stock rudder surface area was too much at higher speeds so he was making an adjustment. His wife was there looking on and I looked at her and she gave me a hug and a big wink... and raised her shoulders. :roll:

 

[Levitation]

Now that's my kind of seaman. Theory is dandy but a saw is handy. It is raining here and still dark out but I am off to the airport to see if any of the usual suspects will show up after early mass.

 

[ozoner]

My dock buddy has bolted a large piece of aluminum plate to his R-25's rudder as he was convinced this would help with the low speed maneuverability and docking task. He doubled the surface area of the rudder in this way. I suggested that he might find the rudder too sensitive at high speeds... and he agreed but wanted to test things out.

Yowza... When you add that much surface area, you are also vastly increasing the amount of potential force that can be put on the rudder; both torque on the rudder tube and side forces that can act on the bearings and/or hinges. And on a planing boat, the extra area also has the potential to cause some flutter vibration which can subtly shake your steering gear to pieces.

I think the fact that this extra area didn't cause damage to the steering systems says something about how well Ranger builds their boats.

 

[baz]

The R-25 does handle well in calm and rough seas.

In Aug 2010 we crossed the Strait of Georgia with some other Tugs -- it was one of the earlier Desolation Sound cruises.

On the way over the Strait of Georgia waters from Pender/Poet's Cove (CN Customs marina) to Gibson were very nice and calm and David Baker on Karma took a movie at my request of our R-25 going at speed past him. He mistakenly left the camera running so please excuse that portion... :lol: The movie file is a bit long at 81 seconds long and some 94 MB in size.

http://dl.dropbox.com/u/94810017/Movies/LaxeyTakenByDavidBaker.MP4

On the way back across the Straigt of Georgia we traveled with Bob/Nita in their Nellie Too R-29. The going was quite rough with 20 kt winds and 4-5' waves at times. We at first tried a quick east-west course as that was the shortage, but the winds and waves picked up and started blowing on our port beam, so we turn more southerly into the wind and waves that added maybe another 60 to 90 mins for the crossing... but made the going safer and not so much rocking & rolling. We maintained a speed of around 8 kts under these conditions. The R-25 handled things admirably although I must say I was very tired after the crossing. I used the auto pilot's Heading feature for the most part as it was far more comfortable doing this rather than me wrestling the wheel for hours while standing and keeping my balance. The auto pilot did a wonderful job, and was pleased to have it.

Here's a short movie of the much rougher crossing on the return trip. It's 19 seconds long and some 38 MB in size. This was before the winds and waves really picked up. Note the variation of the boat's speed at the top of the Chart Plotter screen as it varies from 6 to 9 kts as a result of the steering up, over and down the waves. There were many times when water splashed up right over the cabin. The wipers were kept on for most of the crossing while I kept a careful eye on Nellie Too on my port bow.

If you look closely at the Chart Plotter you can see the black track line that represents the course we took crossing from west to east to arrive at Gibsons. Also, the pale purple line is the Garmin's safe course I configured if we were to take the shortest course line over to the Gulf Islands -- and one we did not take as you can see where my boat is heading in a more southerly line to counter the wind and waves hitting on our port side all the time.

http://dl.dropbox.com/u/94810017/Movies/CrossStraitGeorgia.AVI

I actually found the rougher crossing quite exciting. At one point my starboard dock line become lose and dropped into the water and started trailing. Bob noticed this and radioed me about it, saying it would be wise to haul it back in to avoid it tangling with the running gear. So with the boat on auto pilot I carefully stepped back into the cockpit and with one hand held the grab handle above the starboard step down and leaned out & down as far as I could to grab the line. My 1st mate was terrified I was going to fall in. 😉 I was a bit scared also as I got completely drenched and was fully stretched out trying to catch/grab the flailing line. I did manage to grab it after a while with the boat bouncing all over the place and tied it to the grab handle as a quick solution to the problem.

My wife stayed in the V-berth area for most of the rough crossing doing her cross word with one of our Wire Hair Fox Terriers while the other one hunkered down under the dinette table and kept a very watchful eye on me and what I was up to.

The R-25 ever since that crossing has given me great confidence in her capability in handling rough weather conditions.