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Old 08-14-2013, 05:21 AM   #41
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The Pilgrim style boat is inshore only , so the best attribute of steel would be its repairibility after hitting a lock wall, or a hard grounding.

BUT the maint required of steel would be there 24/7/365.
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Old 08-14-2013, 06:45 AM   #42
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The Pilgrim style boat is inshore only , so the best attribute of steel would be its repairibility after hitting a lock wall, or a hard grounding.

BUT the maint required of steel would be there 24/7/365.
Agreed......steel in a smaller boat is a real coin toss...

It's nice to romanticize about boat...whether a weekend warrior or a "Great Lakes Pilot"...it's great to enjoy working on maintenance or brightwork more than actually getting underway....

Not so great when somebody actually thinks their perception of boating should be everyone's...not saying this to you FF...just in general.
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Old 08-14-2013, 01:09 PM   #43
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Hi Tad,
This idea of utilizing a 'removable insert' of UHMWP (Ultra High Weight Molecular Weight Polyethylene) plastic came to me after having used it for a rudder stock frame on our Firefly trimaran. We had a kick-up rudder on that vessel, and the rudder shaft had to held in place vertically, it had to allow the shaft to rotate very freely, and it had to rotate up backwards out of its slotted position in the transom of the hull.

The natural tendency was employ a SS frame fixture that fit the transom slot and could pivot up rearwards. It would also have bearings mounted it its frame to carry the rudder shaft. And it needed another element that would allow the frame as a whole to rotate during kick-up.

Then I said, why this somewhat complicated metal frame arrangement with separate rudder shaft bearings, etc. Why not just band saw a thick piece of UHMWP to the size I seek to fill that slot in the transom for this kick-up rudder, and drill the appropriate holes to accept the rudder shaft, and the kick-up bearing shaft.

Bottom line, I ended up with a single material piece of tough plastic to replace a somewhat involved SS fixture, and it could be fashioned with a common band saw and drill press, it cost a fraction of the other alternative, and it was virtually free of marine fouling by its very nature.

I think something like this could be fashioned for the twin damper fins I'm proposing.


(PS: I really began to think about this as an idea to add a 'sailing centerboard' onto those 2 motorsalers I like so much,...to keep their drafts low, while adding bit more sail area, and a more central pivot point when tacking, etc. I had twin centerboards on my 37' catamaran, and I do know some of the difficulties of keeping them anti-fouled. I also know of bearing and water-tightness of same with my CB on the trimaran design, and several other vessels)
Hum.....yes, it could certainly be done, but the devil is in the details, and unless the boards are big and of high-aspect ratio (highly loaded) they will not work as well as some folks would want.

How big is the board? How big is the piece of plastic (I know it's available in rod and bar)? How is the plastic held into the case? And how is the board controlled?

For 20+ years I have been designing fiberglass centerboard cases in cold-molded wooden boats. These cases are lined with strips of UHMWP fitted tight to the board shape so that it does not bang around. Generally the fouling inside the case is minimized by the lack of light. We figured out that a hydraulic cylinder on the pivot pin (with spring and sheer pin), inside the boat using a standard stuffing box, is a good way to control the board.
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Old 08-14-2013, 10:30 PM   #44
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Hum.....yes, it could certainly be done, but the devil is in the details, and unless the boards are big and of high-aspect ratio (highly loaded) they will not work as well as some folks would want.
My thought was, unlike a sailboat board that is more highly loaded developing leeway resistance, this 'powerboat board' is only trying to dampen roll,...and not needing the air-foil shape of the sailing one. So it could be just a 'flat plate' if that proves to be the easiest?

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How big is the board? How big is the piece of plastic (I know it's available in rod and bar)? How is the plastic held into the case? And how is the board controlled?
It also comes in big sheets of various thickness. I think I used 1.5 or 2 inch thick stuff for my rudder frame.

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For 20+ years I have been designing fiberglass centerboard cases in cold-molded wooden boats. These cases are lined with strips of UHMWP fitted tight to the board shape so that it does not bang around.
I've know of quite a few such uses, but my thoughts were why attach various strips inside the trunk,...why not fill the whole trunk up with a 'centerboard assembly' fashioned from this material.

For instance I'm thinking the 'bearing' around which the board (or fin) rotates could just be a very short length (width of inside of trunk) UHMWP rod inserted thru round hole in thick sheet of UHMWP that makes up the 'assembly'. The sides of the trunk keep this 'pivot bearing rod' from shifting side-to-side without any other parts or penetrations thru the trunk. All self-contained within the trunk cavity.


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Generally the fouling inside the case is minimized by the lack of light.
That's what I thought as well, and why I figure one would only have to pull the UHMWP centerboard assembly out ever 2-3 years to do a cleaning of the trunk walls.


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We figured out that a hydraulic cylinder on the pivot pin (with spring and sheer pin), inside the boat using a standard stuffing box, is a good way to control the board.
I had hoped to have very little penetrations of the trunk cavity to the inside of the hull. And where deemed necessary they would be made thru the upper 'edge' of the trunk cavity that was preferable designed to be substantially above the WL of the vessel.

The CB trunks on our Louisiane 37' catamaran were well above waterline and had removable top plates. With such an arrangement the centerboard/fin 'assemblies' could possible be withdrawn and serviced even while the vessel remained in the water.
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Old 08-15-2013, 05:27 AM   #45
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Although I have not built one I think an extra wide centerboard trunk could be built into most displacement style hulls.

The case would be fitted with a Maurice Griffiths style lifting board and fitted with fittings that would allow the board to take an angle of attack inside the CB case.

Air, hyd or even electric would force the board into resisting the roll of the vessel.

Grounding would not knock a hole in the hull as hyd fins have done ,
and when underway in modest conditions the board would be raised for zero drag.

Sizing the board to work both underway and at anchor might not be possible , without the complexity of a board that could be dropped further at zero speed.

If done on the initial build the cost of stability would be very modest.
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Old 08-15-2013, 06:00 AM   #46
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Dampening Fin

I was hoping a retractable fin of about this size would be enough to dampen the roll quickly,...not so much actively prevent it, but dampen it from oscillating.

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Old 08-15-2013, 06:15 AM   #47
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I was hoping a retractable fin of about this size would be enough to dampen the roll quickly,...not so much actively prevent it, but dampen it from oscillating.

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Don't think it would do squat if not active...would have to be probably 5X longer and up to even start to notice. I assume the deeper it gets the more effect it would be noticed, but becomes harder to engineer.

Not that I'm an NA...just a backyard boatbuilders eye...
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Old 08-15-2013, 06:24 AM   #48
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You are going to tell me that pulling/pushing two fins this size sideways thru the water is not going to do anything to slow the roll or dampen it ?? I beg to differ with you!
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Old 08-15-2013, 08:35 AM   #49
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You are going to tell me that pulling/pushing two fins this size sideways thru the water is not going to do anything to slow the roll or dampen it ?? I beg to differ with you!
OK...so now we have 2 opinions...we'll see where it goes from there...I'll be interested to know what the other NA's think. I'll grant that they might do something...just not enough if they were fixed.

But I'll bet even money that that size fin is active at great cost...why spend all that money if a fixed one would do? I'm holding my breath...
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Old 08-15-2013, 06:16 PM   #50
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If redesigning from scratch, why not a gyro-stabilizer?
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Old 08-15-2013, 07:15 PM   #51
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Solving roll problems has existed for years, and many methods have been experimented with. I'm not going to claim to be very knowledgeable about the subject, as I come from a sailing background where we always accepted heeling and more motions than do many powerboat owners.

So I'm not going to pretend to solve the rolling problem here with what ever device. I simply presented the 'static fin' idea as one that should dampen roll to some degree, and my idea for a retractable fin had grown out of an idea I had been working on for a retractable centerboard arrangement for a couple of larger ocean-going motorsailers I want to work out.

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If redesigning from scratch, why not a gyro-stabilizer?
I've been keeping an eye on this Seakeeper gyro development for some time as I have been a proponent of 'flywheel energy storage systems' for many years.

Certainly one of these Seakeepers could very easily be installed on the Pilgrim. It just needs a considerable electrical supply to get up and running,....less to maintain it. Here are 3 videos I picked out.

The first two give a side-by-side look at boats rolling. When one looks at these, I think you have to imagine that some sort of bilge keel or bilge fin should be able to at least dampen some of this rolling action once it starts. The third video gives a nice explanation to how the Seakeeper Gyro System works.







How it works:
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Old 08-15-2013, 08:05 PM   #52
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Continuing with the thinking outside the box, if we would need lots of electricity for stabilization - build with diesel electric propulsion.
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Old 08-15-2013, 08:17 PM   #53
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I believe Bolger has published a few power designs with retractable centerboards/fins.
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Old 08-15-2013, 09:42 PM   #54
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I believe Bolger has published a few power designs with retractable centerboards/fins.
Interesting, I will need to take a look when I have some extra time. Any specific books that you know of?
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Old 08-15-2013, 09:56 PM   #55
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Diesel Electric considerations

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Continuing with the thinking outside the box, if we would need lots of electricity for stabilization - build with diesel electric propulsion.
If you had put forward that thought a few years ago, I'd been right on it.

In general the technology as a whole hasn't worked out to be that efficient as originally claimed. And it does complicate things a bit. There were lots of long discussions on some other forums, and some very good articles in Professional Boatbuilder magazine by Nigel Calder.

Sure would be nice to have a single diesel-electric unit supplying power for propulsion, power for thrusters, power for AC, power for gyro stabilizer, etc. But I think it gets a little complicated for this little ship that I was hoping to apply the KISS principal to.
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Old 08-15-2013, 10:01 PM   #56
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Salty that is indeed outside the box. There was a very positive article in PMM several years ago. Too expensive for me to be sure but I got a bit pumped about it thinking about twin screws w single engine and a gen for get home. Would be a good setup for the go fast go slow types too.

Bilge keels should have a very limited effect on rolling. Look at the keel on Willy and observe that it is much bigger than bilge keels if I were to put them on but Willy rolls plenty fine big keel or no. Unless one is in a river changing course seems to work quite well. There seems to be a mentality to need to control things totally. Look at Marin. I don't think he did but he set out to eliminate anchor dragging completely and is convinced he has. Everyone's looking for that magic goo in a can that will never succumb to weather. Boats roll and for the most part I think we just need to make the best of it. And if rolling really bothers you the beach will be there despite global warming and then there's the Great Harbor boat.
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Old 08-16-2013, 09:27 PM   #57
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When I asked the designer of the Pilgrim 40 (possibly it was his son Mike, but I believe it was Ted) about stabilization for my boat on Lake Michigan, his advice was that I ought to be able to have a first class time of staying put at any harbor on the lake for way less money for whatever time it took for the lake to settle down. Advice I have come to believe.

For a completely new KISS coastal cruiser with similar size and configuration I'd be inclined to have something for stabilization designed in. That I would not come to the same conclusion as Mr. Gozzard is questionable. No boat does all things best.
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Old 08-16-2013, 09:56 PM   #58
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Optional Mount for Gyro Unit

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For a completely new KISS coastal cruiser with similar size and configuration I'd be inclined to have something for stabilization designed in.
Interesting observation from a fellow who has owned at least 2 of these vessels I believe. I'll keep that in mind.

Notice on their video 'How it Works', one only needs two good stringers to mount the gyro unit to, and those existed for engine mounting in the original vessel design. I would retain 2 such 'main frame stringers' to provide vessel rigidity in the fore-to-aft axis.

So the gyro-unit might be placed in the compartment with its electric supply (generator), just ahead of the main engine. Or it might be placed under the aft 'porch' deck.
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Old 08-16-2013, 10:33 PM   #59
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The gyro probably is good but probably works best on a very round (half round) hull. W a stiff hull like the IG or GH the righting moment there would be a great battle between the hull chines and the shape of the water under the hull.

On this boat I'd think the gyro would work very well. Notice how far the boat heels w just the pole hang'in out.
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Old 08-16-2013, 11:48 PM   #60
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the gyros work on everything...the first couple tests and videos were of sportfish with very flat runs aft and square chines....worked like a champ..if you can believe the marketing...

they resist rolling...that is their nature so it doesn't matter the shape if the roll never starts or is severely limited.
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