Roll Stabilization

[Portager]

I'm trying to decide what roll stabilization to use on Portager and I would appreciate inputs from the list.

Since the Admirable isn't too keen on rough riding boats, good roll stabilization is a definite requirement. Since I need roll stabilization underway and at rest and I can't afford active roll stabilization that leaves steadying sails and paravanes. Since Portager will have a get home sail, I could use the sail for roll stabilization and avoid the added complexity of the paravane outriggers and launching and recovering them while underway.

So the main question is, which would be the most effective roll stabilization option. The sail or the paravanes?

Thanks in advance for your comments.

Cheers;
Mike Schooley

[Willallison]

I have very little experience with roll stabilization beyong the use of a relatively small steadying sail that is aboard my fathers 36ft Cheoy Lee 'trawler'. The sail did have a noticable effect but the boat doesn't roll too badly anyway so we only used it a few times for the fun of it.
I would have thought that paravanes would be a much more effective stabilization system, but there are definite downsides to their use - such as a reduction in fuel economy and the danger that can be involved when they come out of the water.
The main reason for my post however is to suggest that you check out a couple of the recent issues of passagemaker magazine ( http://www.trawlertravel.com/cgi-bin/site.cgi? ) They had some very good articles on the design, installation and use of paravanes. (Can't remember exactly which issues sorry...)

[Willallison]

'was just looking at their site myself and noticed that the current (May / June) issue has an article dedicated to this very subject

[Portager]

Thanks for the response.

I think the need for roll stabilization is more dependent on the sea conditions and the distance between ports than the craft. I have heard from people that have cruised extensively that paravanes were mandatory on the West coast of the US but rarely used on the East coast.

You are right about the risks/danger involved in launching and recovering paravanes and the impact on fuel consumption. In addition, on a semi-displacement hull, I'd need to slow down to displacement speed in order to use them.

I have done enough research to be 99% convinced that I don't need paravanes and I'd rather not have the additional equipment to erect and stow every time I launch and recover the boat.

My main concern is that I have heard that it can be very expensive to retrofit paravane outriggers onto an existing hull that wasn't designed for them. I think I'll have Portager designed and built to accommodate paravanes but leave them off until I decide I need them.

Cheers;
Mike Schooley

[Willallison]

Sounds sensible.
Once again I suggest a look at one of the passagemaker articles. (and once again I don't know which one!) It details how an owner designed, built and fitted a set of paravanes to his trawler. Well worth a read.
Have you considered fitting non active stabilisers to the hull? It would add to the wetted surface, increasing drag, but I would have thought that it would be more effective than the steadying sail. Depending on design, it would also allow for beaching of the boat - on the other hand, it may also complicate trailering....

[Portager]

Yes;

I am considering bilge keels. These will provide passive roll stabilization and improve the performance of the sail to windward. The bilge keels are more effective than small steadying sails but less effective that a large sail. In addition the inertia of the mast and rigging also help.

In addition they allow the hull to stand straight on a flatbed trailer, which could solve a parking problem and make it easier to ferry the truck and trailer.
Cheers;
Mike Schooley

[davidjgray]

Dear Portager

I spent 5 years in Brown Brothers working on fin, tank and rudder roll stabilisation. If you send me the outline parameters of your vessel (length, beam, hull midship, GM, Displacement, max speed, cruising speed) I can run some simplified simulations to show you the comparative advantages of fin, tank or rudder roll stabilisation potential. We have helped Wesmar inthe past, and they have a very competitively priced system for small vessels of your size.

Best regards

David Gray

[Portager]

David;

Thanks for the offer.

In the intervening 20 months since the previous post on this thread, a few things have change. One, I am now leaning towards active fin stabilization, but I’ll also have paravanes onboard for stabilization at anchor. I decided against paravanes because there have been a few mishaps retrieving them while underway. I’m leaning towards active fin stabilization because they are claimed to be the most effective option and the Admirable has a bad back.

The Admirable and I have decided to make Portager large enough that we have the option of living aboard after retirement. Therefore, our plans are now to make Portager 64’ long with a 12’ beam. The Metacentric height (GM) should be less than 5’ from the keel. Displacement will be 32,000 lbs light and 42,000 fully loaded. Speed will be 12 knots @ full load and 13.5 knots light. Long range cruising speed will be 8 knots.

Regards;
Mike Schooley

[Willallison]

Bloody Heck Mike!...64'..! Can I come watch you back her down the ramp! :D

Have you looked at gyroscopic stabilisers? (Think that's what they're called. Mitsubishi makes them...I think...)

[davidjgray]

Dear Mike

I have run an enquiry routine, and attach the results. We note the Block Coefficient appears very low so perhaps you could check our input data and make sure we have everything correct.

You will note that we have shown perofrmance results for two sets of fins. They both give good performance in regular seas (about 90% stabilisation - shich is the market standard). You will not however that in irregular seas, this reduces to around 60% which is quite normal. In other words if you actually measured RMS roll before and after switching on the stabilisers, you would measure about 60% reduction rather than 90% in sea state 5. The larger fins do have a slight performance advantage in these larger seas as the fins are able to provide more lift before becoming saturated.

The gyroscopic stabilisers are produced by Mitsubishi, and were fitted last year to a luxury yacht in Italy. I think 3 were fitted down the length of the vessel. My impression of them is they are heavy, use a lot of power, and take up quite a bit of space. They have been around for a long time, but have never really caught on.

best regards

David Gray

[FAST FRED]

The latest issur of Professional Boat Builder has a great article in the various forms of stabilazation.

A Combo would probably be best , long bilge keels to resist rolling at anchor & underway , a slosh (Framm) tank doesn't take too much room , and a mast for beam winds would be first choice.And perhaps get home power.

The paravanes could be simplified so launch & recovery was very easy , rather than a task.

The active fins are just another electric item with limited life hyd goodies and a HUGE price tag.

While it may sometimes work OK , parts in Patagonia may be a hassle , as may the first time you run aground or hit a Sea Land box at sea.

For cruising systems should be in depth , so the loss of any one does not ruin the voyage.The Bilge keels and slosh box have NO maint requirements.

FAST FRED

[davidjgray]

Hi

We have a tank model in our time domain simulator. I have added in a tank 1m long & full width of the vessel. results attached.

The tank as sized only reduces roll by around 10%. Tanks can be effective, and are not reliant upon boat speed. However, there are disadvantages to roll tanks such as audible sloshing noise, reduced static stability, increased rolling in long seas (low frequency), internal space requirements (best position is high up midships), increased displacement (typically around 4%) resulting in increased fuel consumption.

We haven't received our copy of PBB yet, but our general advice is there is no such thing as a free lunch in stabiliser selection - whatever method you choose has an impact which has to be weighed against the benefits and your operational requirements.

Have you considered Rudder Roll Stabilisation?

Regards

David Gray

[Portager]

Will;

How about if I post a streaming video to my web site? Just don’t expect to see what’s on the cutting room floor:). I know that 64’ is a lot to transport, but if I make Portager nice enough, then I can convince the Admirable to live aboard and we can sell the house and retire earlier. We are still studying trade-offs, but our current range is 54' to 64'. At this size I expect to use lift launches more and boat ramps less. I’ll also park Portager at my local boat ramp, which the turning radius and ramp length (at high tide) to launch up to 75’. I will have to pay for two parking spaces though :mad: . I agree with David, gyro stabilization is brute force and it takes up too much room and adds too much weight. The need to make Portager transportable means we need to utilize the interior space efficiently and minimize weight.

David;

I think the block coefficient is screwed up because, 1 I gave you the LOA instead of the LWL which should be ~62’, 2 I gave you the overall beam instead of the beam at the waterline which is ~10’ and 3 the full load weight of 42,000 lbs is really for a 54’ length the weight for 64’ scales be 50,000 lbs, but since 50,000 lbs will require a larger tow vehicle I am hoping that we can find a way to keep the weight down to 42,000, 4 Portager is a light weight boat for her water plane area so the block coefficient should be a little low. Also the GM is a worst case number. I expect to get it lower since the air draft is <9’.

I started reading the Wesmar installation manual to get more info, but I ran out of time. I don’t plan to have 3 phase power onboard, actually I don’t plan to have an AC generator onboard, but I will have a hydraulic pump on a PTO shaft. Do you know if I can power the fin actuations directly? Also, I could not find info on Wesmar’s folding stabilizer fins. I think they will make transport highway easier since they would normally be sticking out like blades on a chariot.

FastFred;

It is good to hear from you again, but I have to agree with David. All roll stabilization options involve tradeoffs and active stabilization appears to be the most effective option. If I decide to go with twin props to reduce draft, then I would probably use bilge keels, but that would be primarily to protect the props and I’d still opt for active stabilization. OTOH, reducing draft produces directional control issues in heavy seas so that’s another tradeoff. I had considered sails for roll stabilization and a get home sail, but the rigging is a pain to erect and stow for launch and recovery and I’m already pushing the height limit for transportability. Stowing the mast would be very difficult so I opted for an auxiliary engine instead of the sail. The advantage of active roll stabilizers is they do not add height and they are very effective. The Admirable has a bad back so the more stability means fewer restrictions on Portager’s allowable sea state in the Admirable-onboard operational mode.

Regards;
Mike Schooley

[FAST FRED]

"I had considered sails for roll stabilization and a get home sail, but the rigging is a pain to erect and stow for launch and recovery and I’m already pushing the height limit for transportability. Stowing the mast would be very difficult "

With a Motor sailor the rig is very low and a full battened sail would help with the area .

Simplest I have seen to handle a mast off the shelf is a flag pole raising unit from the local Skool.

These can lift a 30 40 ft mast with ease by turning a crank.
There is a 1/4 of circular toothed gear about 3 ft in diameter, and a small toothed wheel atached to the crank.
Unfortunatly the ones I have seen were galv , and too heavy for you , but aluminum might be avilable.

The other EZ solution is a Lutchet. In this case the mast is pivoted as in a tabernakle , but the heel of the mast pivots to the keel and has some counterweight.

The "trick" is a hatch that opens alowing the mast to pass thru the deck std. on old Thames barges for sailing under bridges!

AS a set of floper stoppers works well and requires a "mast" for a good angle for retreval ,
and a get home sail requires a mast , a combination into one unit would make sense.
Roller jibs can easily be made to store easily, simply have them built with light chain to roll arround instead of hard to coil wire.

Are you planning to live in the boat while on a trailer? as an RV?



FAST FRED

[Portager]

“With a Motor sailor the rig is very low and a full battened sail would help with the area.”

This is a perfect application for “Junk” sails which are low and fully battened. They use an unstayed mast which eliminates the extra rigging and the sails are much cheaper than conventional sails. I went a long way down that road before I decided I just don’t want to have to tend sails anymore. In addition stowing the mast and sail(s) below the 13’ 6” legal height limit on the trailer was going to be a big problem. Keep in mind the keel will be about 1’ 6” off the ground.

”AS a set of floper stoppers works well and requires a "mast" for a good angle for retreval ,
and a get home sail requires a mast , a combination into one unit would make sense.
Roller jibs can easily be made to store easily, simply have them built with light chain to roll arround instead of hard to coil wire.”

My setup will be similar to the Dashew’s design which is described at http://www.setsail.com/dashew/Deck_Tour.html . I’ll have a stub mast on centerline and outriggers on the outside corners of the deckhouse. The stub mast will extend down to the keel and it will be nested so that the extension sections stow inside the fixed outer cylinder. The center mast erection mechanism will probably be pneumatic (compressed air) with locks at the end of travel. In the stowed position the top of the mast will be below the roof line so that the radar and running lights will be at or below the roof for transit. The height of the mast will be sufficient to provide a lever-arm to erect the outriggers which will stow either for or aft, depending on layout. The mounting point for the outriggers will be below the roofline so that in the stowed position they will be below the roof.

”Are you planning to live in the boat while on a trailer? as an RV?”

Yes, it has always been our plan to be able to stay aboard while on the trailer. Originally, this was to provide accommodations while in transit. We figured finding a place to park for the night would be easier that finding a hotel with room to park the boat and parking the boat and disconnecting the truck to drive to a motel would be a hassle. Now, the plan is to provide the ability to stay aboard for extended periods. This puts additional requirements on the boat/trailer combination, but that may be a separate thread.

Regards;
Mike Schooley

[brian eiland]

In the intervening 20 months since the previous post on this thread, a few things have change.
The Admirable and I have decided to make Portager large enough that we have the option of living aboard after retirement. Therefore, our plans are now to make Portager 64’ long with a 12’ beam.

Oh, how our boats grow!

I mght suggest you contact Dave Gerr and Steve Dashew, both who are designing 'cruising power craft'. Don't recall what they are using.
Opps, just found this http://www.setsail.com/dashew/stabilizing_gear.html

An excerpt from that ProBoat article, "One reason sails work well is the fluid dynamic forces go up with the square of the speed (ed:rolling speed). the portion of the sail near the top of the mast is traveling through the air very fast due to the long distance from the roll center (roughly the waterline), so the forces generated by it are large"

[brian eiland]

We don't see that many photos of 'salty old vessels' in their element. Here's one experiencing problems with its power supply to its stabilizing system.

Sure makes one believe in having a back-up system that's not dependant on an active power supply.

...and this isn't even a BIG sea

[Portager]

Brian;

Yes, boats have been known to grow when you add water. In my case the Admirable is scared of small boats and she is happy every time it grows (maybe I should rephrase that?:). I think we are close to the limits for transportability without an escort vehicle, which is where the transport cost start to escalate.

Most stabilization systems are powered off 3 phase AC power, so you need the main engine for propulsion and the generator for stabilization.

Portager will power the stabilizer electrical systems off the battery bank. The hydraulics will be powered by pumps on a PTO on both the main and auxiliary engines, so if I have either engine I should have propulsion and stabilization. If the hydraulic or electrical systems fails, the paravanes are the backup stabilizers.

Regards;
Mike Schooley

[Richard Petersen]

Brian and Portager. I see that old salt leaning. Why is not, a manual hand crank irreverseable worm drive provided to return it to at least a neutral position? That is suicidal in bad weather. Does the manufacturer show them their boat in that condition after installation? We simply do not have enough USCG rescue boats to run down all these boats with gadgets in them.

[davidjgray]

That is the most powerful stabiliser system I have ever seen. Usually stabilisers are sized to give the vessel a theoretical ability to have a static heel of between 3 and 5 degrees (in other words if both fins go hard over in opposit directions then the vessel will be suject to a constant heeling moment which is proportional to the square of the speed - so if your control system fails in this dramatic fashion then to return upright you simply stop.) The systems I have seen have a mechanical locking device to move and hold the fins at zero degrees in the absense of hydrualic power, which for small yachts is typically taken from a PTO rather than a 3 phase electrical power unit as is common on very large yachts and ships.

Looks to me like this vessel was performing a roll test, or someone fitted the stabiliser roll sensor back to front which produces a similar effect.

Of course you do have some redundancy with a fin system. You can always hydraulically isolate a problem fin and continue operating on the other.

Cheers

David

[brian eiland]

Looks to me like this vessel was performing a roll test, or someone fitted the stabiliser roll sensor back to front which produces a similar effect.David

Actually this photo came from a relatively new magazine "Power Cruising", and was reporting on the Atlantic Rally sponsored by Nordhavn this past summer. This vessel lost electrical power to her Naiad stabilizers.
-----------------------------------------------------------------------
An excerpt: "Mather worked his way to the sea strainer for the primary bilge pump. He removed it and handed it to Sue. As she began cleaning it, she noticed the blockage was odd. Most of the material looked strangely familiar. Then the realization struck: It was shavings and dust from the boat’s manufacture. As Mather worked through the lazarette, the Spencers pieced together the events.
When Uno Mas went over, her port side was momentarily submerged. Seawater forced its way aboard via the engine-room vents, through the lazarette vents on the outside of the hull (which had been plugged with sponges for the passage), and past the lazarette’s hatch gasket in the cockpit floor. The water pushed into tiny spaces never before accessed, collecting construction shavings from the far reaches of the bilge. The primary bilge pump simply couldn’t handle the load. Salt water filled the bilge up to the engine’s oil pan. The high-water alarm sounded, and the large-capacity emergency pump started throwing water overboard. With the primary pump working again, Mather moved farther into the storage space, where he found the inverter fried completely black from its saltwater bath. There was no fire. Relief.
The cooked inverter explained the last part of the mystery. The part’s failure meant no power was getting to the cooling pump for the Naiad stabilizers, which promptly shut down.
Problems Solved — Not
Uno Mas was not sinking, and she was not on fire. But without stabilizers in a brutal, heamy sea, The Fearless 40 was more than just uncomfortable; she was downright dangerous. John had the ship aimed into the oncoming wind and waves to minimize the battering while they assessed the emergencies at hand, but that had put them off course. Any farther afield and Uno Mas wouldn’t have enough fuel to make the remaining distance to the Azores. Getting on course without stabilizers put her at the mercy of a savage sea.
--------------------------------------------------------------------------
If I were to consider electrical drives for stabilizers, I might have a look at the 'new generation' DC motors, and in fact the whole systems approach of smaller 'DC' generators and motors discussed in the Dec/Jan issue of Professional Boatbuilder magazine under an article entitled "Diesel-Electric Technology". Lots of good material to think about.

I also took note of this description, " engine-room vents, through the lazarette vents on the outside of the hull (which had been plugged with sponges for the passage)". How do the engines breath properly in this situation. I once had one turbo charger fail on a Chris Craft with a couple of big Cat diesels. The exhast gases leaking from the failed turbo quickly filled up the engine room and clogged the too small inlet air vents, which promptly shut down the other engine for lack of good air. Took some time to get the mess cleaned up enough to get back under power. Luck would it the seas were calm out in the Gulf Stream. Sure would not have been pleasant in a northerly.

This reported incident was a serious situation which could have resulted in abandoning the ship for many owners....just another reason I like the concept of motorsailers over trawlers for REAL ocean going boats.

And I'm always amazed by the descriptions of sea state. They call this a 10 to 12 sea. Doesn't look like that to me in the photo....maybe that's the top of the crest to the bottom of the trough, but technically that's twice the average wave height...so wouldn't this be a 5-6 foot sea. terrible to lose your ship in that sea state.

[water addict]

If the boat has not been built yet, would a retractable fin like a centerboard, daggerboard, bilge boards, or leeboards be an option? If you are going to use in blue water and draft is not an issue, a deep fin would keep drag low for the amount of roll damping you would get. Also, could be retracted when not needed.

Simple operation, low cost, low risk, high benefit/cost.

[Portager]

I think what your suggest could be accomplished by locking the roll stabilizer fins at the zero deflection angle without increasing draft, however static fins are far less effective than actively actuating the fins to produce lift forces to counter the induced roll torque.

Draft is important, even on a blue water boat, because once you cross the ocean you still need to be able to get into port and access coastal anchorages. In the case of Portager, draft is very important because it increases the height on the trailer.

Regards;
Mike Schooley

[Richard Petersen]

Old salt, UNO MAS, is so bad, I don't know who to blame more. They were playing Russian Roulette, without being told. Sad, very, very, sad. That is ocean cruising, to the Azores? I have heard enough Gross negeligence by every body who designs, builds, retrofits and then owners who think they can afford to buy experience with money to enjoy the boat . No one is in charge of the boating industry. It is a joke compared to cars or aircraft. Good bye.

[FAST FRED]

"No one is in charge of the boating industry."

Thank GOD "no one is in charge", as there can be advances and progress that is unavilable in the auto or aircraft industries.

Sure they create yet less efficent engines sfor the Smog Police , but what real advances have they has in the past 30 years?

At least in boats folks can experiment with advanced concepts like foils , or retro concepts like long skinney 1920's style Commuters with out pleasing some dead brained burocracy "Design & Materials Revew Board".

FAST FRED

[FAST FRED]

One method of roll stabilization I have contemplated ,
but never seen in practice could be a center board with a wider than usual box.

If the board could be "steered" as a rudder , to damp the roll.

Advantage , in power failure it could be locked ahead or lifted , but when working should provide roll stability (if large enough) with out the danger of protruding wings sticking out .Going aground or a submerged log would be painless.


If balanced (pivot located aft of leading edge ) the force required should be quite small , so backup mechanicals could be cheap enough to carry complete spairs.

FAST FRED

[ivansalasj]

Dear all,

I am currently doing some research in active fin stabilizers for zero speed. I am using a 33 m power boat and a variety of cfd programs to simulate the roll motion. I am currently at the stage where i need to choose reasonable fin dimensions for this particular yacht and then i will need to implement the damping produced by the fins on the overall roll motion. If anybody has any suggestions to my current stage i will be great ful to hear them.
Thanks, Ivan

[SamSam]

but I’ll also have paravanes onboard for stabilization at anchor. I decided against paravanes because there have been a few mishaps retrieving them while underway.


I just read somewhere about the different methods of stabilization and one of the big drawbacks to paravanes is if one of them quits working due to being tangled up or lost (broken cable), in certain conditions the other can keep going deeper and deeper resulting in capsize.

[water addict]

Centerboard, daggerboard, bilgeboards can be easily retracted. Powered roll stabilization devices are inherently complex, and require a fair amount of maintenance.

[Portager]

SamSam

The incidence of paravanes fouling and/or failing while underway is very low if the equipment is properly maintained, however it is much low while at anchor. In addition retrieving paravanes while at rest is much easier that while underway.

As far as I know active stabilizers are the most effective means of stabilizing while underway and second place is far behind. However, active stabilization does not work without forward motion. While at anchor paravanes are the most effective although a steadying sail may be a close second.

Regards;
Mike Schooley

[FAST FRED]

The simplets is a Training Wheels tri concept, where the amas are simply to stop the boat from rolling.

Perhaps with a simple hinge ski they could offer increased active roll controll underway.

Having had a Tri in rolly harbors & it was grand.

The monohulls would set all kinds of ground takle to attemt to point into the big swells, and still rolled like logs!

WE simply went up & down , far easier to live with.

Today in a monohull of affordable size I think the dink (say a 13ft Whaler) could simply be hoisted a foot or so on a boom amidships to give great roll resistance, although it would make the dink easy to steal.
(Recovering New Yorker)

FAST FRED

[Guillermo]

Dear all,

I am currently doing some research in active fin stabilizers for zero speed. I am using a 33 m power boat and a variety of cfd programs to simulate the roll motion. I am currently at the stage where i need to choose reasonable fin dimensions for this particular yacht and then i will need to implement the damping produced by the fins on the overall roll motion. If anybody has any suggestions to my current stage i will be great ful to hear them.
Thanks, Ivan

Ivan,
Have a look at the SIS system: http://www.stabtech.com/
Regards,
Guillermo.

[brian eiland]

Sorry I just have a tough time selling myself on going to sea in a 'strickly-power' craft. I keep coming back to the motorsailer concept (http://boatdesign.net/forums/showthread.php?t=4499&highlight=motorsailer) if abandoning a primarily sailing craft.


Here's a short excerpt from a gentleman who is living his dream of taking his trawler across the Pacific to Australia. Some have been following his story for a couple of months.

Gentle Wind - Moving again, breaking down again

Well, on Monday we finally got our electrical repairs completed, and got fueled up on Tuesday. (Rarotonga fuel price is US$3.50 per USGallon.) A new crew member arrived on Wednesday, and we headed out on Thursday afternoon, next stop Tonga.

Five hours out to sea, the Naiad stabilizers decided to go Tango-Uniform on us - the second time since we left California back in June. We decided to keep on going, since a return to Rarotonga was not something we wanted to contemplate after having just spent five weeks there waiting for the electrical repairs. Fortunately, we had wonderful conditions, with smooth following seas and light winds on our stern almost all the way.

Anyway, we have a new crew member on board. More to the point, I've demoted myself to first mate and we have a new skipper on board. I decided that I didn't want the skipper's job any more, since I've spent just about every waking second taking care of everyone else and the boat, too, but not having any time for Number One (me!). So, Stuart is now skipper, and I'm just a hired hand. We'll be completing the trip across the big pond to Australia, but at that point I'm just going to have "deleted" shipped back to the states and put up for sale. Too many things keep breaking, and the repair bills (on top of the fuel bills and the crew's grocery bills!) are breaking the bank.

It might sound like I'm giving up, but I don't look at it that way. I've proven to myself that I can do this, but I've also learned that it's a lot more than I had bargained for.

We'll be here in Tonga for just a few days, fueling up and waiting for a weather window to Suva, Fiji. We hope to find someone there who can figure out the problems with the Naiads so we can have some stabilization on the way to New Caledonia and Australia.



Brian added
I just don't want my source of propulsion and my source of stability dependant soley on a fuel engine. I think this posting addresses the KISS principle as well.

[masrapido]

Or, you could simply build a nice catamaran and solve the problem, portager. And get more space and speed along the way.