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Old 05-06-2021, 12:51 PM   #41
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Ofer,

What would you be attaching it to?
That’s the question you ask.
This would need some oak inbd hull stringers and the bilge keel through bolted. This would act as a clamp. The steam bent ribs may not be strong enough.
William Garden drew small rolling chocks for my boat in 1950(I’ll find the drawing) and the drawing notes say “do not attach to frames”
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Old 05-06-2021, 12:59 PM   #42
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If rolling chocks are such a "sure thing".......why don't pleasure boats come with them from the factory ?? I have a hard time thinking that the original designer of a hull didn't include something so simple if it made that big of a difference. The usual answer of course is cost, but the cost of installing them during the construction can't be that significant when you are talking about boats that costs 3/4 of a million dollars or more when new. Especially since it would give you a selling point over a competitor.

So.....why do you guys know more than the naval architects employed by Mainship, Selene, Grand Banks etc ?
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Old 05-06-2021, 01:02 PM   #43
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Originally Posted by Benthic2 View Post
If rolling chocks are such a "sure thing".......why don't pleasure boats come with them from the factory ?? I have a hard time thinking that the original designer of a hull didn't include something so simple if it made that big of a difference. The usual answer of course is cost, but the cost of installing them during the construction can't be that significant when you are talking about boats that costs 3/4 of a million dollars or more when new. Especially since it would give you a selling point over a competitor.

So.....why do you guys know more than the naval architects employed by Mainship, Selene, Grand Banks etc ?

As you move into faster boats, I'd expect the drag penalty to become significant.
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Old 05-06-2021, 01:32 PM   #44
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Originally Posted by Benthic2 View Post
If rolling chocks are such a "sure thing".......why don't pleasure boats come with them from the factory ?? I have a hard time thinking that the original designer of a hull didn't include something so simple if it made that big of a difference. The usual answer of course is cost, but the cost of installing them during the construction can't be that significant when you are talking about boats that costs 3/4 of a million dollars or more when new. Especially since it would give you a selling point over a competitor.

So.....why do you guys know more than the naval architects employed by Mainship, Selene, Grand Banks etc ?
Cost...my $3 million 123 foot boat came with rolling chocks brand new. The boats you point out all have paravane options. Maybe they designed boats that don’t need them...better yet maybe the $150k for an electronic stabilizer has a better ROI? Using a big boatbuilders (who design to marketing plans) might not be best for your boat.
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Old 05-06-2021, 02:33 PM   #45
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William Garden drew small rolling chocks for my boat in 1950(I’ll find the drawing) and the drawing notes say “do not attach to frames”
“do not attach to frames”

I agree completely. part of the design should allow for recovery from an impact and not sink the boat.
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Old 05-06-2021, 02:50 PM   #46
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If rolling chocks are such a "sure thing".......why don't pleasure boats come with them from the factory ??
One issue is they are difficult to mold into the hull and must be added on. This does not fit in well with the flow of a typical gel coat female mold process. As you get into the Selene, Fleming, Nordhavn class, another $50K for more effective active stabilization makes more sense.

Yacht design is much more influenced by fashion and the marketing department than any practical consideration. At least in the PNW, you will find a high percentage of small work boats with them.
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Old 05-06-2021, 06:37 PM   #47
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One issue is they are difficult to mold into the hull and must be added on. This does not fit in well with the flow of a typical gel coat female mold process. As you get into the Selene, Fleming, Nordhavn class, another $50K for more effective active stabilization makes more sense.

Yacht design is much more influenced by fashion and the marketing department than any practical consideration. At least in the PNW, you will find a high percentage of small work boats with them.
So well said, I agree 100%. If I ever read Passegemaker magazine I would never have to my boat.
Fashon and current trends make for the desire to trade up�� notice the next Range Rover outfitted for the Serengeti at Safeway, hauling kids to the soccer game. The current line of rugged deep sea trawlers are similar. They may be able to voyage to Japan, but will do weekends instead. Nothing wrong with it, is just the way we are marketed to.
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Old 05-06-2021, 10:40 PM   #48
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So well said, I agree 100%. If I ever read Passegemaker magazine I would never have to my boat.
Fashon and current trends make for the desire to trade up�� notice the next Range Rover outfitted for the Serengeti at Safeway, hauling kids to the soccer game. The current line of rugged deep sea trawlers are similar. They may be able to voyage to Japan, but will do weekends instead. Nothing wrong with it, is just the way we are marketed to.
Hey Cap,
Still hoping to run into you out there or catch you at PH.

I am of the same sentiment with simple (elegant) design and systems. I think it is possible that chocks are discussed less in the pleasure boat arena because not everyone gets it right. I think chocks must be well thought through and they must be a part of the overall stability designed into the vessel. I am not sure they can stop very much a hull that really wants to roll due to a harshly chined hull, poorly located metacenter which can be based on either design compromises or poor judgment in loading even after a decent design, or other characteristics that result in the need for high force mechanically active stabilization equipment added to a hull after a build
Both of my steelers have chocks. On KLEE WYCK they are long but shallow in depth. The boat has a very pleasant roll on its completely round bilge, but it does roll.
LIBRA has appendages that serve at least a couple of roles. They serve as the keel coolant reservoir and I believe they contribute as chocks to reduce roll as well. They are a much deeper box type keel and much more vertical than those on KLEE WYCK. They are combined with a hull with just a small bit of chine and one which has a very low metacenter and massive ballast. Besides 10 mm steel build in her substantial center keel and the bilge keels, she has a double bottom with a total of 1700 gallons (17000#?) of liquid laying in her bottom. The very heavy 10 cylinder diesel motor and 2200# gear have their tops 2.5' below sea level. And, she is packed full of poured cement to boot.
This boat was conceived in order to be comfortable in the North Sea and without paravanes, fins, or Magnus moving parts.
She does not roll much and what she does, you can barely perceive in terms of comfort.
I think this whole package is what results in that.
KLEE WYCK has chocks but still rolls a bit though comfortably so. I have yet to send a pax to the rail.
LIBRA has chocks and does not roll.

So, if you decide to go with chocks.....hire someone very smart to think about what they should look like and where they should go on your hull.

Both pictured here.
Attached Thumbnails
klee wyck stern 2.jpg   keels1.jpg   Keels2.jpg  
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Old 05-07-2021, 01:49 PM   #49
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I had them put on my 38' trawler by Independent Marine of Vancouver Island, BC. Three techs arrived with pre-fab fins (about 10" wide) and installed on the chines in less than a day. Made a big difference to the corkscrew action when going over wakes, or slop/roll when at anchor. Only on the stern quarter did the vessel rock as it had before installation. Very pleased with the result. Since then that 13 ton boat has been in slings many times and the fins have not dented due to the straps. No issue at docks - they don't protrude beyond the fender diameter. And there was no change to fuel consumption. A no brainer upgrade.
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Old 05-07-2021, 03:45 PM   #50
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There is a reason they don't dent in the slings: they are probably thicker than the hull. I had to cut some vent ports in mine (installed by the same guys) because the underwater exhaust was getting trapped. They are around 1/2" thick glass, not dainty.
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Old 05-07-2021, 04:29 PM   #51
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We use to own a 50' canoe stern wooden boat that came with batwings as they are called. They were plates 1/2" thick that were on struts bolted straight out from the bottom of the keel. They worked great. I took them off one year...just to see the difference and it was quite remarkable. Put them back on the following year. Close to 3000 lbs total weight. We lost 1/2 knot of speed but well worth the increase in comfort. You could also put the boat onto a beach with no fear of it rolling over if the need came up. I can send you pictures if you're interested.
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Old 05-07-2021, 05:23 PM   #52
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We use to own a 50' canoe stern wooden boat that came with batwings as they are called. They were plates 1/2" thick that were on struts bolted straight out from the bottom of the keel. They worked great. I took them off one year...just to see the difference and it was quite remarkable. Put them back on the following year. Close to 3000 lbs total weight. We lost 1/2 knot of speed but well worth the increase in comfort. You could also put the boat onto a beach with no fear of it rolling over if the need came up. I can send you pictures if you're interested.
Bill
Would love to have a picture
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Old 05-08-2021, 08:58 AM   #53
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We use to own a 50' canoe stern wooden boat that came with batwings as they are called. They were plates 1/2" thick that were on struts bolted straight out from the bottom of the keel. They worked great. I took them off one year...just to see the difference and it was quite remarkable. Put them back on the following year. Close to 3000 lbs total weight. We lost 1/2 knot of speed but well worth the increase in comfort. You could also put the boat onto a beach with no fear of it rolling over if the need came up. I can send you pictures if you're interested.
Bill
I would love to see pics. Sounds similar to our 58' canoe stern..:-)
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Old 05-08-2021, 02:12 PM   #54
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We use to own a 50' canoe stern wooden boat that came with batwings as they are called. They were plates 1/2" thick that were on struts bolted straight out from the bottom of the keel. They worked great. I took them off one year...just to see the difference and it was quite remarkable. Put them back on the following year. Close to 3000 lbs total weight. We lost 1/2 knot of speed but well worth the increase in comfort. You could also put the boat onto a beach with no fear of it rolling over if the need came up. I can send you pictures if you're interested.
Bill
I to would love to see a pic
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