I am thinking about putting sheets of foam in the quarterberths and in the forepeak to make my boat unsinkable. If I used luan plywood to hold the sheets in place there could still be room for the porta-potty and some storage in the main "cabin".
Question is: Would this work? How much foam would I need to keep my boat afloat?
If it would work I think it would be a good trade off (space for safety).
The volume you'd need to make it unsinkable will be a lot more than the space under the bunks and forepeak.
From memory, For air you'd need circa 50 cu ft as an absolute minimum to keep it from going under.
Gordon
Pacman,
I'm a 16 sailor as well. Just wondering what specific concerns you have that make you want to do this.
I did that when I first got the boat and it pretty much took up the forepeak and under the bunks . The question is how high do you want the boat to float. I had a bunch of 4" thick sheets of 4 x8 blue Styrofoam leftover on a job site so I added about 25 cubic feet, just enough so I would have the boat floating with me if I ever sprung a significant leak a few miles out. But as my confidence in the boat grew I got rid of it.
A lot of floatation Styrofoam sites have calculators on them
Brian
A CP 19 weighs 2000 lbs. not counting motor and cargo. Water weighs 62 lbs. per cubic foot. So to make a 19 unsinkable you would need about 32 cubic feet of foam. That's the equivalent of a solid block bigger than 3' on each side.
For this reason, you'd have a hard time finding any keelboat that's unsinkable. Much easier with a powerboat - no heavy keel!
Wes
Quote from: MHardy on July 21, 2016, 06:28:41 PM
Pacman,
I'm a 16 sailor as well. Just wondering what specific concerns you have that make you want to do this.
I plan to sail on some glacial lakes in Northern Minnesota where I have seen uncharted rocks just below the surface.
If I put a big hole in the boat I would want it to "float" high enough so I would be able to stay with the boat until help arrives.
the 16 is a rather "tender" boat in that it will heel pretty fast before it hardens up. with its small sail area i doubt it would get knocked down if the skipper was paying attention. in heavy wind have the mainsheet in hand and keep the hatch board in and buttoned up. as to making the boat unsinkable, i dont think it is practical. couple that 450lbs of concrete with a cabin full of water, shes gonna go down.
Hi Guys,
This was discussed in the Legacy section some time ago but should be easy to find. Calculations and formula for how much foam was needed are posted there. The amount of extra foam needed in a 16 would actually be fairly minimal I expect. In the Legacy, which seems to me to be basically just an updated 16, there is enough foam put in during construction to float it if holed, probably. The factory think this but can't say it as testing it requires them to sink a boat or some other equally destructive test.
Cheers,
Pete,
Thanks for that thread. It contains the formulas needed to calculate floatation and other good information.
Based on the information in that thread I can see that the big foam blocks I had planned for the quarterberths will float the boat nicely.
When I had a CP16 and a CP23 and went offshore, I carried an inflatable water ski tube as a "liferaft". Inflate it ahead of time and keep it in the cabin. It won't float the boat, but it will float a couple of people. it also happened to be bright fluorescent pink which would be easy to see. That, and a handheld waterproof VHF radio were my emergency bailout gear if it ever came to that. I never tried tubing behind the 16, but my CP23 pulled the kids just fine!
The glacial lakes in northern Minnesota are generally pretty shallow except for some, but in the deep parts you will not be able to hit anything that would hole your boat. I have sailed the most northerly of them with my weekender and can report that for the most part the dangerous reefs and rocks are well marked both on the water and on the charts. I also contemplated floatation for my 16 mostly because I would like to use it on Lake Superior when the water is dangerously cold. Not that it isn't cold year round, but in the spring is when I would like to at least day sail on the big lake. I think you could add enough floatation to keep it off the bottom, and if you figure out how to stuff all you gear in around the foam, I don't see why you shouldn't do it. Especially if it gives you peace of mind.
Al
I wonder if you could fill in the bunks with air rafts (e.g. like pool rafts) and if that would provide the flotation required. I have thought of using such an air raft. 1500 lbs would be 680 liters, which would mean 340 empty 2 liter bottles.
I agree that for my sailing it wouldn't be worth it.
Sorry, 2 liter bottles sounds a little mundane to me. You'll need a little more imagination to make a real splash. How about beer cans instead? If you scout around some pickup beds you should find more than enough empties. I'd fasten them all along the inside of the hull and claim it to be your beer can collection, and no one would be the wiser, except that they would need to be upside down. Don't forget that if you are sinking to hurry and finish off the last full six-pack to add to the flotation total.
You know, I always thought an ejectable keel could be a real good idea.
Seriously, I wouldn't lie awake at night worrying about that. I'm not sure the sixteen would have enough speed or weight to do much more than bounce off of an underwater object. There is a lot of experience on this forum, and I've never heard mention of a 16 sinking from being holed while sailing. If anyone has, please share the details to make a judgement if it is a real concern or not.
Quote from: Potcake boy on August 03, 2016, 06:57:22 PM
I'm not sure the sixteen would have enough speed or weight to do much more than bounce off of an underwater object.
I hit a stump (I think) underwater at about 4-5 mph while motoring. Stopped the boat dead. Small chip out of the keel. A rock to the waterline might do a little more damage, but I think you're probably right, unlikely that you'll produce a significant hole in the boat unless you wash up on a rocky shore and get beaten by waves. I could envision a crack that seeps some water, but these hulls are pretty thick.
I cruise on Superior with my 16 without added floatation, and I'm planning to cruise for a couple days on Lake Kabetogama (one of those N. MN glacial lakes) this fall without added floatation.
If you're still paranoid I think pulling a small inflatable or a small kayak would be better than taking up precious cabin space with foam. Then you would have a way to get to shore easily too.
Quote from: NateD on August 04, 2016, 10:01:00 AM
I think pulling a small inflatable or a small kayak would be better than taking up precious cabin space with foam. Then you would have a way to get to shore easily too.
Good plan!
Thanks
I have sailed Kab. Make sure you get a detailed lake map for it. The good ones have all the shoals and boulders marked on them. Kabetogama is pretty shallow overall and will do a lot of damage. Keep an eye out for waves that don't look quite right, and changes in the color of the water. It is a very beautiful lake and large enough to take a while to explore. You should enjoy the trip.
Al
I second the kayak approach. Used to tow a 12' SOT behind my 19 and didn't see any significant effect on performance. The SOT was easy to board and egress from the stern ladder (which by the way is an important piece of safety equipment).
I just did a three day two night trip to another northern Minnesota lake that I would recommend to other CP 16 sailors. Birch lake is located in northern Minnesota just outside of Babbit. It is a reservoir for the iron mine there and follows the Birch river valley. The lake is about 15 miles long and twists and turns so that you will see every angle to the wind if you go the distance of the lake. There are very few cabins on the lake, so it looks for the most part like a wilderness lake. Camping is either at designated campsites, or wherever there is a nice spot. I anchored out both nights. It is a glacial granite lake, so the anchoring can be a bit sketchy, but there are a lot of hidey holes that can provide protection from the wind and waves. There are only two launch ramps for such a big lake, one on either end, and the boat traffic isn't terrible. They never see a sailboat up there, so they all notice one which is a safety benefit. Also, most of the dangerous rocks and reefs are marked on the water. A detailed lake map is necessary to get the most out of traveling there as well as locating the rocks that might not be marked.
Anyway, this is one of the most beautiful lakes up there for sailing small shoal draft boats. No permits or fees involved, and stay as long as you like. It is certainly worth a look see.
Al
Duckie,
That sounds like a real jewel compared to all the restrictions and sailboat hatin' you find elsewhere nowadays, especially here in Florida. It was recently proposed as a law that there will be no anchoring in certain state-owned waterways because some wealthy folk bought a politician from an unrelated part of the state to sponsor the bill. One of these locations is a popular place for cruisers to await fair weather for the Bahamas crossing. I guess that's the story of minorities. Where is BOATUS after all these years of support? Down here it is the Southwinds magazine that champions sailors with information and editorials.
If I had a small trailer boat, and lived anywhere near there, it would certainly be on my list.
Fixed heavy keel of about 40% of the boat's total unlaidened weight will pull the boat under when filled with water NO MATTER HOW MUCH FOAM is used.
And I would guess that the deck being pulled up [weight of the boat hung from the deck] to float the boat would pop all the rivets holding the deck and hull together.
On a CP-19 about two thousand+ pounds of water [two hundred and thirty gallons of water] would need to be displaced by the foam.
There is no U.S. Coast Guard or any boat manufacture requirement to make any Com-Pac unsinkable.
You want a boat like that, find a double hulled French ETAP sail boat.
Don't let this be you~! I grew up staring at this Winslow Homer print that hung in my parents schooner's saloon.
Craig Weis
I understand the concern for safety sailing border lakes that are on the Canadian Shield. Granite doesn't give if you hit it. Knocking a hole in a CP is not out of the question, but the consequences of that should not be tragic on any of those lakes, if a person wears his life jacket, and the water isn't too cold.
I mostly sail my Weekender up there, a boat with a considerably weaker hull than my CP, with no more concern than I would have anywhere. I have knocked over my Weekender to test it just in case. Fully swamped, it sits high enough that I could start the motor and head for shore. With the cabin closed but not sealed I could, if I act quickly enough, right the boat and continue sailing with minimal water sloshing around. Probably even with a hole in it somewhere, a CP 16 could make it to shore if one is quick about it. None of those lakes are that big that it would be too far to swim. The kicker is that the water is too cold to do that most of the year. Being able to stay with a crippled boat is the best alternative in cold water, but it needs to float to do that. I am sure that a CP 16 could be made to float after taking a catastrophic hole in the hull, but you would give up a lot of storage space that would make cruising problematic on anything longer than an overnighter. It would be possible to inflate bags the would fill the entire interior of the boat which would keep it afloat thereby negating the need for foam. How that could be done is left to the imagination, but it could be done.
My CP is the only one of my three sailboats that will go to the bottom and leave me alone in the water. I have resigned myself to that idea and have made preparations for that event. That in the end might be the best answer to this question.
Al
Duckie, just duckie. " if one is quick about it. " Hummm.
The United States Power and Sail Squadron and the U.S. Navy's 1933 Blue Jackets Manual states the following.
a~ The Rule of 50. It is ... 50 years old-50 degree water-50 minutes before hypothermia takes your life. Adjust the 50's as required.
b~ Distance viewed over water is distorted in two ways. Standing on deck and viewing an object the mind sees one distance. Turning your back, bending over and viewing the same object from between spread legs the mind sees two times the first distance. This is the true distance to the viewed object.
Which kind of explains why swimmers start out on a voyage and end up dead from exhaustion.
'Know Your Ships' is a facebook page. [foto]
Craig Weis
A typical ETAP [ unsinkable, they will float down to the deck/hull line and still be sail-able ] looks like a spaceship to me. Very little tradition.
Craig Weis