Notice:
The advice given on this site is based upon individual or quoted experience, yours may differ.
The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.
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?
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
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
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.
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
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 Örebro (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"
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
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.)
...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
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?
...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
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
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
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.
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
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.
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.
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?
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
Notice: The advice given on this site is based upon individual or quoted experience, yours may differ. The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.