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Flexing of the cabin
- Thread starter Bryant
- Start date
matt_unique
New member
Bryant":2ajzo1o2 said:I posted this message but it didn't seem to come up.
I have a 1999 C Dory 22 and the cabin seems to flex alot in moderate seas. Does anyone else have this problem?
Do you mean visible flex while underway or tell-tale signs or cracks?
Bryant":2udxcvrt said:I posted this message but it didn't seem to come up.
I have a 1999 C Dory 22 and the cabin seems to flex alot in moderate seas. Does anyone else have this problem?
What are Moderate Seas? Where is this "flex"??
We need more information: As above, how do you know it is flexing? Where do you notice any changes or movement? Is the floor flexing? Is the cabin top flexing or are the sides flexing?
Agree--we need to know what seas you are referring to.
The Boat should not flex. There have been some boats (very few) which have flexed. But your boat is way out of warranty. There are some things which can be done diagnostically, as well as to repair the boat is there is a problem.
Agree--we need to know what seas you are referring to.
The Boat should not flex. There have been some boats (very few) which have flexed. But your boat is way out of warranty. There are some things which can be done diagnostically, as well as to repair the boat is there is a problem.
On my 1991 22 Cruiser, the cabin sides flexed near the galley counter top. I had to move the counter top away from the cabin side about 1/8 to 1/4 in to stop the squeaky sound.
I owned the boat for 16 years and the flexing never got worse and never caused any cracks or other problems.
I owned the boat for 16 years and the flexing never got worse and never caused any cracks or other problems.
It sounds to me if the boat is pounding. Do you have trim tabs and a Permatrim? If you do,you can put the bow down--and decrease/stop the pounding.
How fast are you going?
The cabin sides are solid fiberglass, and not very thick (maybe 1/4" max)--and if you are pounding the boat, may be appearing to flex. The deck and cabin roof are cored and thus much stiffer.
There are ways to stiffen up the cabin sides--but this involves putting stiffners in place. These could be wood, or fiberglass/foam. But if you are pounding, you may be abusing the boat.
How fast are you going?
The cabin sides are solid fiberglass, and not very thick (maybe 1/4" max)--and if you are pounding the boat, may be appearing to flex. The deck and cabin roof are cored and thus much stiffer.
There are ways to stiffen up the cabin sides--but this involves putting stiffners in place. These could be wood, or fiberglass/foam. But if you are pounding, you may be abusing the boat.
My experience is exactly like Larry's. It did this since it was new. I finally pulled the counter top and sanded the edge where it rubbed on the cabin side.the cabin sides flexed near the galley counter top. I had to move the counter top away from the cabin side about 1/8 to 1/4 in to stop the squeaky sound.
My 1994 CD 22 cruiser will flex like that if I really drive it hard -- it's the pounding -- my fix was to trim the bow or slow down.
I believe it is the same on all the cruisers -- if you approach the boat from the outside as it lies on the trailer and gently pound between the aft and middle window with the bottom of a closed fist you can get some pretty good vibrations and flexing. I actually went down to the dealer to pound the new boats to see if this was unique to my boat when I first discovered it. The new boats flex exactly the same way.
Interestingly, the port side flexes less -- but on my boat I have a teak grab rail between the aft and middle window which I assume is stiffening the boat up in that area.
My conclusion (after pounding every C-Dory I could find in Ventura Harbor) was the flexing was God's way of telling me to slow down. I never found any resulting cracks or loosening of hardware/ windows etc.
Matt
I believe it is the same on all the cruisers -- if you approach the boat from the outside as it lies on the trailer and gently pound between the aft and middle window with the bottom of a closed fist you can get some pretty good vibrations and flexing. I actually went down to the dealer to pound the new boats to see if this was unique to my boat when I first discovered it. The new boats flex exactly the same way.
Interestingly, the port side flexes less -- but on my boat I have a teak grab rail between the aft and middle window which I assume is stiffening the boat up in that area.
My conclusion (after pounding every C-Dory I could find in Ventura Harbor) was the flexing was God's way of telling me to slow down. I never found any resulting cracks or loosening of hardware/ windows etc.
Matt
T.R. Bauer
New member
Everything we make has some flex. Buildings flex, airplanes, bridges, huge ocean ships, and even our C-Dory boats. My 93 does exactly what you guys are describing.
But, the "fix" is very simple as all you have to do is slow down to the speed where it doesn't do it anymore. Our boats do not run through sloppy chop at high speeds very well at all. And once you get that through your head and adjust your actions by reducing your speed, this flexing will become a distant memory. I have no idea what happens if you just ignore it and let the pounding continue. But my intuition tells me it just isn't good.
Others have suggested adding stiffeners and you can. It probably will help. However, the engineers that design things take into account the natural oscillations that ocurr while cars, boats, trains, and planes have while in operation and adding stiffeners may add a problem somewhere else.
Unless you have a serious hull problem, and I doubt that you do, I would just slow down. If you can't just slow down, I think you maybe you should be looking at a deep-v boat as they deal with the chop much better.
But, the "fix" is very simple as all you have to do is slow down to the speed where it doesn't do it anymore. Our boats do not run through sloppy chop at high speeds very well at all. And once you get that through your head and adjust your actions by reducing your speed, this flexing will become a distant memory. I have no idea what happens if you just ignore it and let the pounding continue. But my intuition tells me it just isn't good.
Others have suggested adding stiffeners and you can. It probably will help. However, the engineers that design things take into account the natural oscillations that ocurr while cars, boats, trains, and planes have while in operation and adding stiffeners may add a problem somewhere else.
Unless you have a serious hull problem, and I doubt that you do, I would just slow down. If you can't just slow down, I think you maybe you should be looking at a deep-v boat as they deal with the chop much better.
T.R. Bauer
New member
C-Hawk":xxitz274 said:Are you getting any rush of air out of the v-berth when you pound?
I hope not.
I have a feeling if you are then that area is displacing a lot of air when it moves. That can't be good. I have never had that happen in my boat. Like most C-Dory owners, I would rather go slow anyway.....
As I recollect there was a piece of wood glassed into the hull on the port side for the table suoports.
It would be interesting to see if the newest CD 22 (molded interiors) have as much movement.
I had to retab some bulkheads etc on the 25. I suspect it had been driven at too much speed into chop.
I'm not sure about how much "engineering" goes into this flex type of issue on the small boats. There are laminate schedules which are acceptable for boats this size, and most builders adhere to these. Where-ever the cut cross section of the CD 22 is, would tell us how thick the laminate is. It does not need much strength at this point. Another question is how the aluminum frame window fits in this equation, if any?
Agree, slow down. This is understanding the C Dory boats.
It would be interesting to see if the newest CD 22 (molded interiors) have as much movement.
I had to retab some bulkheads etc on the 25. I suspect it had been driven at too much speed into chop.
I'm not sure about how much "engineering" goes into this flex type of issue on the small boats. There are laminate schedules which are acceptable for boats this size, and most builders adhere to these. Where-ever the cut cross section of the CD 22 is, would tell us how thick the laminate is. It does not need much strength at this point. Another question is how the aluminum frame window fits in this equation, if any?
Agree, slow down. This is understanding the C Dory boats.
T.R. Bauer
New member
thataway":3kj4dcz9 said:As I recollect there was a piece of wood glassed into the hull on the port side for the table suoports.
It would be interesting to see if the newest CD 22 (molded interiors) have as much movement.
I had to retab some bulkheads etc on the 25. I suspect it had been driven at too much speed into chop.
I'm not sure about how much "engineering" goes into this flex type of issue on the small boats. There are laminate schedules which are acceptable for boats this size, and most builders adhere to these. Where-ever the cut cross section of the CD 22 is, would tell us how thick the laminate is. It does not need much strength at this point. Another question is how the aluminum frame window fits in this equation, if any?
Agree, slow down. This is understanding the C Dory boats.
Bob,
You are probably spot on in reference to my engineering comment. I too wonder how much engineering goes into the flex of our boats and whether it is good that it flexes or not. I wonder if the CD engineering guys ever even look at computer models and real word models to see what happens in given situations. It seems that it should. My guess it that type of R&D is beyond the means of the budget. That's ok too as all of us are involved in those real life tests on a daily basis and the boats seem to hold up very well over time. I personally think the boat is very tough, capable, and a nice little ocean boat. It has its little quirks as all boats do, like not appreciating being pounded in the chop and not having its core get wet. But this list is quite short in comparison to other boat builders.
Tim