Bilge Keels

[bogranjac1]

Sure - the double end is a big plus. A big rudder also helps.

My boat can roll terribly in certain conditions; it's all matter of timing. It only gets objectionable when the boat's natural roll cycle equals, or is divisible by, the swell interval. While underway, it's easy to change how often the boat encounters the swell by adjusting direction and/or speed. (or using the sails)
At anchor, I can adjust direction I"m pointed, but if conditions change during the night things can get ugly. The rolling chocks seem to have less effect at rest compared to underway. I've been looking into flopper stoppers of various type to address this, although it is more crap to deal with, and I prefer simplicity.

Auscan, you could easily just hang a single flopper stopper off the end of your boom if you wanted. This would keep things simple and easy. I often have just deployed one of my pair and found a pleasant improvement.
I'm sure double enders would handle a following sea better than a transom boat. I enjoy a following sea and love surfing down the face of the rollers - I hit 10 knots once !!
But then you know the saying ' gentleman only sail down wind' . lol
Regards.

 

[Fish53]

Auscan, you could easily just hang a single flopper stopper off the end of your boom if you wanted. This would keep things simple and easy. I often have just deployed one of my pair and found a pleasant improvement.
I'm sure double enders would handle a following sea better than a transom boat. I enjoy a following sea and love surfing down the face of the rollers - I hit 10 knots once !!
But then you know the saying ' gentleman only sail down wind' . lol
Regards.

Double enders are the most graceful and pleasing to the eye type of boat in my opinion. Sure you lose a bit of deck but gain a more seaworthy and beautiful boat, and no one wants to be seen having a "flat" a$$.

 

[Rick Hudson]

Rick,that is helpful. Especially as the "Clipper 40" boat I`m considering is quite similar. The Original Owner(OO) had them fitted by a highly reputable yard. Initially midship, later adding shorter fins aft. Seller(S),still friends with the OO(good sign!), says OO fitted same to a Clipper 48 replacing the 40. Unfortunately no pics available ,barring a swim I can`t eyeball them until haulout, if I get that far. S says movements after initial movement are well damped.

Got any pics you can post? I envisaged them attached to the hull below the chines. Yours extend outboard mounted on the chines, or did I misunderstand?

Here are some construction photos of rolling chocks/static fins. It was just over a day's work to install for 3 techs. The fins arrived pre-formed and were trimmed to fit the chines.

 

[ben2go]

Here's some info from George Buehler the designer of the Diesel Ducks.


Bilge Keels

 

[Fish53]

Here's some info from George Buehler the designer of the Diesel Ducks.


Bilge Keels

I second that opinion, thanks for sharing.

 

[Delfin]

I don't have a very good picture of mine, but the below kind of shows them. I cut out around 8' or so of them when I installed the stabilizers, but they are at around a 45 degree angle, 8" deep with the holes you can see in the photo.

The only operation I had with just them and not stabilizers was in transiting from Long Beach to Ensenada, but since the hull was empty of everything but the engine, I doubt that experience means much. I suspect they have an effect, which is why they were standard on these vessels, but I personally would doubt how much of an effect. My guess is that it was a "better than nothing" sort of decision to install them originally.

 

[clyde]

bilge keels...we have a 41 skookum, [built in port townsend] full keel round bottom, 5" draft, they are attached to the hull at the turn of the bilge, about a foot plus below the water level on the hull, 2" in from the stern, 26ft long, and start to taper in, about 6 feet from the fwd end...we have pictures, if anyone is interested, i would need to make a copy, and mail them via snail mail...they sure work! we go places we would`nt have before! met a guy that had hard chines, and had the keels attached to the hard chine, just below the water line, worked great!! so if any one wants my good pics, i`ll need a physiical address...clyde

 

[BruceK]

Thanks for posting the pic Jdoc. I`m concerned the "fin" extends beyond the hull and see the Yard saw the need to support the fins.
I appreciate all the contributions. If I had these on a boat think I`d have pics too. Seeing the boat in the water may not tell me much, even if I get in the water with it. Now there`s a cyclone forecast for the interstate area where the boat is,and we`re committed to flights, hotel, car hire, etc. Just all part of life`s rich pageant.

 

[clyde]

on my hull, they are about 2" foward from the end of the hull, on commercial boats/hulls, they put them flush with stern...something about nets/web, etc...clyde

 

[Fish53]

Thanks for posting the pic Jdoc. I`m concerned the "fin" extends beyond the hull and see the Yard saw the need to support the fins.
I appreciate all the contributions. If I had these on a boat think I`d have pics too. Seeing the boat in the water may not tell me much, even if I get in the water with it. Now there`s a cyclone forecast for the interstate area where the boat is,and we`re committed to flights, hotel, car hire, etc. Just all part of life`s rich pageant.

I wish you the best of luck getting through that weather, and be careful, remember "one hand for the ship and one for yourself".

 

[AusCan]

Auscan, you could easily just hang a single flopper stopper off the end of your boom if you wanted. This would keep things simple and easy. I often have just deployed one of my pair and found a pleasant improvement.
I'm sure double enders would handle a following sea better than a transom boat. I enjoy a following sea and love surfing down the face of the rollers - I hit 10 knots once !!
But then you know the saying ' gentleman only sail down wind' . lol
Regards.

Yes - I love getting the boat up on a wave as well, although I found my limit on some big rollers off Yorke Peninsula which broached me. It went from ecstasy to terror in about a second.

My rolling chocks don't seem to do much at anchor.
Hanging a flopper stopper off the boom is an option, but with my gaff rigged setup, it has fixed backstays which limit my boom from swinging out to only about 60 degrees without major stuffing about. I'm considering a purpose built rigging to support a pair of f/s's.

How's your flopper stopper rigging holding up?

 

[markpierce]

I don't know how effectiveness is measured, but with the rolling chocks on my boat, she still rolls like %^#! without the sails. ...

Yes, sails can help.

 

[bogranjac1]

Yes - I love getting the boat up on a wave as well, although I found my limit on some big rollers off Yorke Peninsula which broached me. It went from ecstasy to terror in about a second.

My rolling chocks don't seem to do much at anchor.
Hanging a flopper stopper off the boom is an option, but with my gaff rigged setup, it has fixed backstays which limit my boom from swinging out to only about 60 degrees without major stuffing about. I'm considering a purpose built rigging to support a pair of f/s's.

How's your flopper stopper rigging holding up?

Flopper rigging has been exceptional so far, no stress apparent on the fittings or boat. I think maybe the trick is to have ropes that have some 'give' instead of S/S cables attaching the floppers to booms and on to the boat.
Auscan do u have a spinnaker pole onboard? If so use a halyard from mast top and hang to flopper off that. Your rolling chocks 'might' be positioned a little too far under the roll of the hull and lose some influence due to proximity to the keel. Not saying I don't think they work - just think could be more effective positioned higher.
BruceK, have u found a boat u like? can u tell us the make/ model so I can do a search to see what she is plz?
Regards.Brett

 

[AusCan]

Your rolling chocks 'might' be positioned a little too far under the roll of the hull and lose some influence due to proximity to the keel. Not saying I don't think they work - just think could be more effective positioned higher.

Regards.Brett

I'd agree, Brett.
They are also a bit too vertical for maximum roll reduction. I'd think that a 90 degree angle from the hull would be most effective.

The designer may have had to reduce the effectiveness to avoid any potential "tripping" issues when falling off a wave.

I don't have a spinnaker pole for the flopper stoppers, but I'm keeping an eye out for a 2nd hand one (or two).

 

[BruceK]

Off topic but interesting, the Queensland Weather Bureau Cyclone OMA Warning. Not something we see further south in Sydney:

Tropical Cyclone Forecast Track Map Page (1)

 

[Jdoc]

Thanks for posting the pic Jdoc. I`m concerned the "fin" extends beyond the hull and see the Yard saw the need to support the fins.
I appreciate all the contributions. If I had these on a boat think I`d have pics too. Seeing the boat in the water may not tell me much, even if I get in the water with it. Now there`s a cyclone forecast for the interstate area where the boat is,and we`re committed to flights, hotel, car hire, etc. Just all part of life`s rich pageant.

The spray rail was designed to be inside the outer envelope of the deck edge so there are no problems with tying alongside walls and pilings. They create more lift and increased top-end speed by 1.5 knots. They attenuated rolling at rest and displacement speeds. Main downside I’ve noticed was more pronounced wave slap on the beam when traveling in moderate to large side seas at displacement speed.

 

[ben2go]

I second that opinion, thanks for sharing.

You're welcome.

Yes, sails can help.

That sail set up could make some nice shade while cruising.

 

[Salish Ranger]

I have had passive stabilizers installed on our American Tug 34 for three years now. They were installed professionally by Independent Shipyards here on Vancouver Island, but they traveled to my marina to do the work, and brought everything pre-manufactured ready to go. Completed in one day and launched the next, the improvement in fwd.quarter and beam seas and wakes of passing yahoos is very much worth the relatively modest cost (under 6K). Rr. quarter seas are not affected as much.They start about 1/3 from the bow and at the stern are about 12" they are hollow, and fill with water. They are very rugged, and slings are no problem at all. Docks are not an issue, as they do not extend beyond the rub rail. There might be a small improvement in speed, but the comfort is noticeable. A 40 foot trawler travelling behind me around Cape Caution asked why we were not bobbing in the Pacific swells the way they were.

 

[Insequent]

I have noticed that a few people have hollow bilge keels. That's fine, but surely they will just fill up with barnacles and other marine growth over time?

 

[RT Firefly]

Greetings,
Mr. sr. Welcome aboard eh?

 

[ben2go]

I admit I am curious about bilge keels. I understand how they are supposed to function. I admit that I don't have enough information to make a claim as to their abilities. I have studied up on paravanes and slosh tanks (anti-roll tanks) enough to know I'd go with paravanes before anything else. I'm strictly speaking of passive stabilization.

 

[MurrayM]

I have had passive stabilizers installed on our American Tug 34 for three years now. They were installed professionally by Independent Shipyards here on Vancouver Island, but they traveled to my marina to do the work, and brought everything pre-manufactured ready to go. Completed in one day and launched the next, the improvement in fwd.quarter and beam seas and wakes of passing yahoos is very much worth the relatively modest cost (under 6K). Rr. quarter seas are not affected as much.They start about 1/3 from the bow and at the stern are about 12" they are hollow, and fill with water...They are very rugged, and slings are no problem at all. Docks are not an issue, as they do not extend beyond the rub rail. There might be a small improvement in speed, but the comfort is noticeable. A 40 foot trawler travelling behind me around Cape Caution asked why we were not bobbing in the Pacific swells the way they were.

Welcome aboard, and thanks for the post...especially the underlined bits

 

[MurrayM]

Here's a 60' vessel built by Independent Shipwrights that has rolling chocks...last 7 photos show them quite well: Boat for sale - Independent Shipwrights Ltd LRC Pilothouse Trawler - 60'

Do they look like yours, salish ranger?

 

[dirtdoc1]

View attachment 85549 This is Coosa board and epoxy

That install doesn't look anything like mine. Here is another install that looks more like mine.

Cheers!

 

[BruceK]

That install doesn't look anything like mine. Here is another install that looks more like mine.

Cheers!

Can you identify the boat? I note the "clinkered" f/g hull.

All the info posted is helpful and generally positive. Wish I had a hauled out pic of the boat I might(cyclone willing) see this weekend.

 

[bogranjac1]

Can you identify the boat? I note the "clinkered" f/g hull.

All the info posted is helpful and generally positive. Wish I had a hauled out pic of the boat I might(cyclone willing) see this weekend.

Bruce,
I think you are in a win / win situation with this boat already having rolling chocks installed.
The current owner or original owner recognised the chocks were advantageous, to date they haven't been knocked off at the pen or fuel dock or somewhere that the captain was not familiar with.
The 'after market' install if we can call it that would have been carried out by very competent installers - none would consider allowing a 'back yard' johnny like me to play with an expensive prestigious craft.
So :- it's recognised that the chocks are needed.
There is little or no drawbacks - otherwise they would have been removed.
Been installed competently
By the way, thx for link....I love the dinning lounge area.

 

[dirtdoc1]

Here's a 60' vessel built by Independent Shipwrights that has rolling chocks...last 7 photos show them quite well: Boat for sale - Independent Shipwrights Ltd LRC Pilothouse Trawler - 60'

Do they look like yours, salish ranger?

The bilge keels on the Independent 60' look very similar to mine.

 

[BruceK]

Thanks Brett. They were designed and installed for the original owner by the Millkraft yard,retained by the current owner who says the original owner put them on his replacement C48. Done in 2 stages, a longer midships section and later a shorter aft section(? not effective enough at first), total cost about $10K.
Yes, the facing lounge/dining area is good, it`s a generally well designed boat.

 

[klee wyck]

I do not have before and after experience with these but I do have a couple of hulls with appendages. I also am not sure if there are formal definitions of these things but I tend to think of the smaller and non vertical ones on Klee Wyck as rolling chocks and the more robust and vertical ones on Libra as bilge keels.

These boats both have nice rides. I have no experience that would indicate the level of improvement over nothing, or a way to compare any attenuation or PIA factor from these as opposed to fins, vanes, or gyros.

I will go so far as to say this: owning and operating these boats has caused me to have a very high level of respect for their NA/designers and builders and for the folks that commissioned these vessels. I have been able to gather some information on the individual that commissioned Libra and his time served in the North Sea demands respect.

Because of this, I am inclined to think that if these appendages are there, it is for good reason. I trust they are doing something that is worth what it cost to put them there.

 

[MurrayM]

I’ve read, somewhere in the distant past, that it’s not just pressure on the bilge keel / rolling chock that dampens roll, but also turbulence on the “non pressure” side comes into play as well.