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Catalina/Capri 25/250 Sailor's Forums

Catalina 25 Specific Forum

swing keel support spring

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Maplesfan
Deckhand

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USA
4 Posts

Initially Posted - 05/22/2017 : 17:51:20

I need a spring to absorb shock from sumps on the shallow lake I'll be sailing on. Can anyone tell me what kind of spring I need?

Thomas A Lomont

Maplesfan
Deckhand

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USA
4 Posts

Response Posted - 05/22/2017 : 17:53:55

Oops! Didn't use spell checker. Should have been stumps. T.L.

Thomas A Lomont

dasreboot
Admiral

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803 Posts

Response Posted - 05/23/2017 : 03:59:54

usually, your centerboard will just rise over the shallow and fall back down. if this is happening a lot, or the distance to fall becomes to great , i imagine that damage to the trunk could occur. Is that what you want the spring for? To lessen the shock of falling?

Todd Lewis
Eowyn 87 TR/WK C25 #5656
ARWEN 84 TR/SK C25 #4031
www.mainsailsailingschool.com

DavidBuoy
Admiral

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USA
707 Posts

Response Posted - 05/23/2017 : 04:48:28

I'm not sure about a spring. But having a pad or something in the back of the trunk would probably a good place to start. I know some that have done it but not sure whom.

Captain Rob & Admiral Alyson
"David Buoy"-1985 C25 SK/SR #5053

Stinkpotter
Master Marine Consultant

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Djibouti
9013 Posts

Response Posted - 05/23/2017 : 06:56:48

In the 20+ years I've followed this forum, I've seen several cases where submerged objects caused cracks in the swing keel trunk from the keel falling off the object after riding over it. You can try the Search function (above-right) looking for threads on the subject--look for words like "swing" and "crack" in the C-25 forum (including archived threads).

Now, I hate to say it, but if you expect to hit some objects, you should probably have a centerboard-type boat with something like water ballast (Catalina 250) or a ballasted trunk keel (O'Day)--not a 1500 lb. swing keel. It's been proven too many times that the structure around the swing keel is not built to withstand much of a free-fall of that long slab of iron. There might be some way to absorb and spread the shock (like a leaf spring?), but I haven't heard of anyone doing it. And even then, every time the keel falls, the basic structure is going to be stressed and weakened somewhat.

Too bad Catalina doesn't still have the very shallow draft wing keel retrofit kit they once sold for swingers... It was expensive, but a number of owners did it--one that I know of after his swinger sank twice in her slip.

Dave Bristle
Association "Port Captain" for Mystic/Stonington CT
PO of 1985 C-25 SR/FK #5032 Passage, USCG "sixpack" (expired),
Now on Eastern 27 $+!nkp*+ Sarge

Edited by - Stinkpotter on 05/23/2017 07:01:14

Maplesfan
Deckhand

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USA
4 Posts

Response Posted - 05/23/2017 : 08:43:58

Thanks for all the replies. I haven't sailed on Grand Lake St. Mary's in Ohio yet, but, the boat club members have warned me that all the shallow stumps are not well marked and are occasionally discovered by sailing over them. This creates a rise and then rapid decent of the swing keel if hit squarely. Members have mentioned that they use a spring to absorb the shock, but, I neglected to find out what size spring they use. I'm about two hours away and was hoping to get a spring now so I can launch this weekend. The good news is we've had a lot of rain and the lake is high to start the season.

Thomas A Lomont

JamesBird
1st Mate

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USA
68 Posts

Response Posted - 05/23/2017 : 12:16:48

I think I'd find another lake to sail on

Jim
Danvers, MA
79 Cat25/SR/SK/(1185)

islander
Master Marine Consultant

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USA
3992 Posts

Response Posted - 05/23/2017 : 13:13:54

To put a spring in is something you would have to fabricate. Catalina never had a spring. I would ask around to see just how they do this.

Scott-"IMPULSE"87'C25/SR/WK/Din.#5688
Sailing out of Glen Cove,L.I Sound

Stinkpotter
Master Marine Consultant

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Djibouti
9013 Posts

Response Posted - 05/23/2017 : 13:57:50

What boats do these members have? And if C-25s, where/how are they mounting the springs?

A "centerboard," which does not provide significant ballast, is a whole different animal from your swing keel in this regard. (As bad or worse is a dagger-board... I hit some object with my Sunfish on a man-made lake years ago--threw my passenger overboard and almost sunk the boat before we could get back to shore.)

Dave Bristle
Association "Port Captain" for Mystic/Stonington CT
PO of 1985 C-25 SR/FK #5032 Passage, USCG "sixpack" (expired),
Now on Eastern 27 $+!nkp*+ Sarge

Edited by - Stinkpotter on 05/23/2017 14:00:58

dasreboot
Admiral

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803 Posts

Response Posted - 05/24/2017 : 05:26:51

I was thinking about this, so i did some research. apparently larger boats with swing keels use hydraulics to raise the keel. After they rise from hitting an object, they slowly fall. Totally unhelpful here, but interesting. this is a quote about a Swedish boat.

"All the Guylines have hydraulically controlled swing keels. On the Guyline 125 this meant that you could reduce draft from 2.4 meters to 1.4 meters. Very practical, specially if you have your boat in the shallow harbour of �rebro (which we had). It can also be used to increase speed during downwind sailing or motoring and it reduces the risk of hull damages if you hit ground, because the keel folds back and takes some of the impact energy. If you are lucky you will just glide over the shallow and then the keel slowly comes down again. This happened to us several times"

Todd Lewis
Eowyn 87 TR/WK C25 #5656
ARWEN 84 TR/SK C25 #4031
www.mainsailsailingschool.com

dmpilc
Master Marine Consultant

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USA
4593 Posts

Response Posted - 05/26/2017 : 05:12:52

I'm one of the guys who experienced a crack in the keel trunk after the keel lifted up and fell back down. I won't go into details. After that I always kept some tension on the keel cable to keep it from smackimg the back of the keel trunk if I hit an object again.
A taut keel cable also activates the cable "speedometer" (cable hum as boat speed increases).

DavidP
1975 C-22 SK #5459 "Shadowfax" Fleet 52
PO of 1984 C-25 SK/TR #4142 "Recess"
Percy Priest Yacht Club, Hamilton Creek Marina, Nashville, TN

WesAllen
Navigator

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USA
222 Posts

Response Posted - 05/26/2017 : 07:36:38

I do the same thing with speed hum. Tells me if I am racing or just cruising.

Wesley Allen
"Breaking Wind"
1982 C-25 SR/TR/SK #2773
Hemlock, MI

pastmember
Master Marine Consultant

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2402 Posts

Response Posted - 05/30/2017 : 15:47:20

Stump thumping? Buy a scow.

Frank Hopper

pastmember
Master Marine Consultant

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2402 Posts

Response Posted - 05/30/2017 : 15:50:42

Has anyone asked you on a Snipe hunt? I think these locals are jerking your chain. NO ONE stump thumps as a routine event of sailing. If a lake is shallow and full of dead trees then it is a fishing lake and you should find a decent place to sail. (I live in Kansa and I know shallow water.)

Frank Hopper

Stinkpotter
Master Marine Consultant

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Djibouti
9013 Posts

Response Posted - 05/30/2017 : 20:08:06

...and I'll repeat: A 1500 lb. swing keel is not the same as a centerboard. The latter is just heavy enough to stay down--the former can break the hull.

Dave Bristle
Association "Port Captain" for Mystic/Stonington CT
PO of 1985 C-25 SR/FK #5032 Passage, USCG "sixpack" (expired),
Now on Eastern 27 $+!nkp*+ Sarge

Edited by - Stinkpotter on 05/30/2017 20:09:06

jerlim
Master Marine Consultant

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USA
1484 Posts

Response Posted - 06/03/2017 : 20:06:12

I can't imagine the amount of energy to push the boat, while the keel is being forced up...I've run aground at low tide once (maybe twice..?) and I don't think the keel budged at all, we just rapidly lost speed as the keel dragged into the bottom. Hitting a submerged tree with the keel would have to be similar to a collision, causing a dead stop...and I am curious, isn't the rudder in danger of being ripped off?

Jerry

Stinkpotter
Master Marine Consultant

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Djibouti
9013 Posts

Response Posted - 06/03/2017 : 21:12:39

quote:
Originally posted by jerlim

...Hitting a submerged tree with the keel would have to be similar to a collision, causing a dead stop...and I am curious, isn't the rudder in danger of being ripped off?

My recollection (easily confirmed or disproved) is the swing keel draws 5', which is a foot more than the fin keel I had, and I'm sure is substantially more than any rudder Catalina provided. But a very shallow object could definitely get them both...

In any case, a 1500 lb. hinged keel isn't going to stop a 5000+ lb. (loaded and occupied) boat. It will cause a significant jerk as its impact pushes it up enough to ride over the object and then do a short free-fall (a second impact). There have been a fair number of reports on this over the years--most due to the damage done to the hull by the fall of the swing keel after riding over the object--not by the keel stopping the boat.

Dave Bristle
Association "Port Captain" for Mystic/Stonington CT
PO of 1985 C-25 SR/FK #5032 Passage, USCG "sixpack" (expired),
Now on Eastern 27 $+!nkp*+ Sarge

Edited by - Stinkpotter on 06/03/2017 21:15:59

WesAllen
Navigator

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USA
222 Posts

Response Posted - 06/04/2017 : 07:11:52

The rudder WILL go up then slam back down. Been there done that repaired that.

(crack in front of keel opening.) I now keep tension on cable so keel is very slightly raise ( hence the hum). I would rather repair cable than hull again.

Wesley Allen
"Breaking Wind"
1982 C-25 SR/TR/SK #2773
Hemlock, MI

Stinkpotter
Master Marine Consultant

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Djibouti
9013 Posts

Response Posted - 06/04/2017 : 08:36:46

quote:
Originally posted by WesAllen

The rudder WILL go up then slam back down...

We assume you mean the keel... (?) I suspect that if it's the cable that tries to stop it, it won't--you'll just have a broken cable or winch, plus maybe a cracked hull (from after the cable breaks), and you'll have to lift the boat out to fix it.

Hmmmmmm... How about a short, very heavy "snubber" at the end of the cable...? I guess it would have to fit into the hole and cable hose. Or maybe something like rubber motor mounts under the winch to absorb some of the shock as the cable tries to stop the keel--possibly saving the cable and the winch? Just noodling...

Dave Bristle
Association "Port Captain" for Mystic/Stonington CT
PO of 1985 C-25 SR/FK #5032 Passage, USCG "sixpack" (expired),
Now on Eastern 27 $+!nkp*+ Sarge

Frank Law
Navigator

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USA
159 Posts

Response Posted - 06/04/2017 : 14:09:50

On a blustery day about 12 years ago in late Oct. I was by myself taking "About Time" to her winter storage . I hit something first with the swing keel then with the rudder the force ripped out the lower gudgeon leaving me with little control . I had to hang over the transom and steer the boat with the motor about 2 miles with a number of sharp turns in the river and creek back to the mooring . It was quite an ordeal and trying to hook up the mooring pennant only added to my trouble Luckily the gudgeon mounting screw hole an piece that tore out were above waterline . I was able to fasten a piece of plywood over the holes and remounted the rudder which almost was lost several times. A week later I was able to continue the 18 mile trip.

Frank Law
Now sailing a sunfish

WesAllen
Navigator

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USA
222 Posts

Response Posted - 06/04/2017 : 15:49:51

Yes, I did mean keel. Anyway I have since hit things with the keel and not had a problem with the cable. But then I change it every 2 or 3 years when hauled out. But that is still easier than repairing the keel housing. If the cable breaks after hitting something it still have taken most of the force out of the drop. I'm no engineer so I can't say for sure. It's just my experience so far.

Wesley Allen
"Breaking Wind"
1982 C-25 SR/TR/SK #2773
Hemlock, MI

jduck00
Captain

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USA
313 Posts

Response Posted - 06/08/2017 : 08:23:54

Take a look at this post. http://www.catalina-capri-25s.org/forum/topic.asp?TOPIC_ID=29405. Is shows the damage and repair after hitting some rocks. The fiberglass is only about 3/8" think on the aft part of the trunk. If you managed to add a spring to it, it would jsut increase the point load on the fiberglass and probably still break through. There has been a few threads on what to do for us swingers and so far I don't think anyone has a good answer. I've personally put a lot of thought into. With out building a new trunk to house the the modifications, I don't think there is much you can do.

Jeremy Duck
The Lucky Duck
1980 SKSR Hull # 1850

Maplesfan
Deckhand

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USA
4 Posts

Response Posted - 06/23/2017 : 08:02:33

Thanks for all the replies. So far the water on the lake is high and hitting stumps is not likely. I've found a couple solutions locally where heavy valve springs and a steel plate are used to soften and distribute the force of the keel dropping. I haven't done it yet as I will be pulling the boat out after the 4th. As for the rudder I have a kick up rudder.

Thomas A Lomont

dasreboot
Admiral

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803 Posts

Response Posted - 06/23/2017 : 09:33:12

quote:
Originally posted by Maplesfan

Thanks for all the replies. So far the water on the lake is high and hitting stumps is not likely. I've found a couple solutions locally where heavy valve springs and a steel plate are used to soften and distribute the force of the keel dropping.

that sounds like a very good idea. and people locally have had success with this mod?

Todd Lewis
Eowyn 87 TR/WK C25 #5656
ARWEN 84 TR/SK C25 #4031
www.mainsailsailingschool.com

Sailynn
Navigator

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USA
178 Posts

Response Posted - 06/23/2017 : 11:55:19

hitting a rock or hard submerged object is one thing. But hitting a submerged tree stump that probably has been rotting for years in the water should be a soft hit. as stated, keep the keel cable tight and be more worried about the tree stumps eating your anchor.

Lynn Buchanan
1988 C25 SR/WK #5777
Sailynn
Nevada City, CA

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