| T O P I C R E V I E W |
| engdockter |
Posted - Feb 17 2007 : 12:56:05
I was raised in south florida around boating all my life, but now that I live in the midwestI have a question I dont know the answer to,I have a 10 meter trojan docked in a marina with about 150 boats of varis sizes from 20 to 60 feet or so, and noticed that about 10 percent of the boats have some type of device under the water at the end of the slip that keeps the water circulating so the slip dosent freeze,and the rest of the boats are froze in the water like mine, does this hurt anything? |
| 50 L A T E S T R E P L I E S (Newest First) |
| sugilbert |
Posted - Feb 25 2007 : 12:43:36
Hey engdoctor, what's happened with your frozen boat since you first asked? Inquiring minds need to know! :) |
| wkearney99 |
Posted - Feb 25 2007 : 12:25:05
Another risk of ice is pier jacking. The ice freezes around the poles. Tides and wave action causes the water to rise. The ice, stuck hard to the poles, pulls them up out of the bottom. Thus having bubblers can protect not only your boat but the piers too. |
| divedaddy |
Posted - Feb 19 2007 : 11:39:42
Mike has it right on the whole in the ice. Further, freezing of water around a boat in a static situation would not increase the pressure against the hull. Damage is done to a hull because the situation is not static - the ice is moving and the boat is moving, and the forces generated when that happens can lead to hull fractures.
When a boat in water gets frozen in, the water hits max density just before it starts to freeze. As it further cools after freezing the density of the ice decreases, i.e., it expands. When all the water has been frozen so that the boat's hull is completely surrounded by ice, then the boat behaves like a bolt within an ice nut. Because ice expands as it cools and the boat should contract as it cools, the pressure between the two should actually decrease, in an otherwise static situation.
Just the opposite is true for water freezing in an engine block or seacock - there you have an expanding ice bolt within a contracting nut situation. That's why blocks and the like crack.
Aside from engine, seacocks, thru-hulls and the like, the real problem for boat hulls comes when the ice moves either due to water movement beneath it or due to wind, and the boat separately moving due to wind or whatever, plus movement against the ice due to water movement just before it is completely surrounded by ice.
The freezing in process will challenge engine blocks, thru-hulls, seacocks, pumps and similar items, but it should not challenge a boats hull. Movement of ice and boat against each other by other forces can and does break hulls. |
| MIke F |
Posted - Feb 19 2007 : 10:13:37
Adrift--You are correct--pressures on the hull are caused by the water inflow/freezing into the space between the hull and the original hole. However if you read some of the comments above you may note that there was a general consensus that a hole in ice will directly shrink--this is simply not true. |
| Adrift |
Posted - Feb 19 2007 : 09:41:54
Mike F,
OK, technically the hole doesn't shrink. It simply keeps getting smaller due to the freezing of additional water exposed along its circumference.
Bottom line, as most hulls are tapered, the pressure being exerted against the sides of the hull would continually rise, and could indeed result in a hull fracture. |
| MIke F |
Posted - Feb 19 2007 : 09:07:02
Adrift_- No I am not saying that since the water underneath the ice will fill in the hole. I am simply saying that a hole in an ice sheet, not continually filled in by water, will increase in size as the ice cools (throughout the temperature range where it expands on cooling).
My point was that the pressures on the hull of a vessel left in the ice, are not due to the original hole shrinking, but due to more complex issues (eg water filling in the hole etc). |
| Polar Skipper |
Posted - Feb 19 2007 : 01:18:51
Papillon - the darned hole in the cabin floor got so big that first the rocking chair went and then the stove followed to the bottom of the lake. Fraid the outhouse is goin to go next. |
| John151 |
Posted - Feb 18 2007 : 20:48:51
quote:
Originally posted by engdockter
1/2 to 1" at the most
I have no scientific knowledge, or real world experience, nor did I stay at a Holiday Inn last night, but I would think that if the ice is too thin to walk on, then it is not strong enough to crush your hull. And I can say with confidence that 1" of ice is not thick enough to walk on.
|
| Adrift |
Posted - Feb 18 2007 : 20:36:56
Mike F,
Are you saying that if I were to place a piece of pipe or a pole upright in a pond, and then the pond froze over at zero degrees fahrenheit, I would be able to easily remove the pipe or pole from the frozen pond as the hole around the pipe or pole would have expanded as the temperature dropped? |
| engdockter |
Posted - Feb 18 2007 : 20:24:40
1/2 to 1" at the most |
| John151 |
Posted - Feb 18 2007 : 20:11:21
Russel - Any idea how thick the ice is around your boat? |
| dritter |
Posted - Feb 18 2007 : 19:41:40
I am not a smart guy, but someone left a boat in the water over a winter on lake erie and there was a crused hull in the spring. |
| JeffR |
Posted - Feb 18 2007 : 19:33:34
Yes, psalzer, so I hear...Thanks, BOB |
| psalzer |
Posted - Feb 18 2007 : 18:13:42
"Actually, Gary, us lowlifes can also send and receive PM's...unless something has changed very recently"
Say "thanks" to BOB!!!! |
| MIke F |
Posted - Feb 18 2007 : 17:35:28
I'm not putting anyone on--just inserting some science into the discussion. Just as a hole in a metal sheet gets larger as the metal expands even though it expands in all directions so too will a hole in ice get larger as the ice expands(of course, ice anomalously expands as temperature decreases while metal expands as temperature increases.
If you put a hole in ice and put in a plastic cylinder in it the ice will expand away from it. Of course if you continually fill in water around the hole ie between the cylinder and the original hole. there will be pressure exerted on the cylinder--the reason for this is that the newly added water,will expand against the original hole in the ice and be forced into compression due to the temperature-dependent negative thermal expansion of water. However that is not the situation being discussed.
|
| engdockter |
Posted - Feb 18 2007 : 17:26:43
Allright enough with the freezizng crap, 38 days till spring,dont that sound peachy!!! |
| rommer |
Posted - Feb 18 2007 : 16:52:18
Mike is assuming that water only expands in an outward direction which is bogus. It expands equally well in any direction. No mater what I prefer keeping ice away from my boat and thru holes.
|
| engdockter |
Posted - Feb 18 2007 : 16:49:18
Thanks to john and everyones input, but Iam hoping john is right, although I still plan on having a frost free slip next year, but being a newbe to leaving a boat in the water in the winter I just had to ask opinions. |
| bruceb |
Posted - Feb 18 2007 : 16:47:20
Mike...go to a frozen lake...cut a hole...put a plastic cylinder in the hole...the ice will form around the cylinder and eventually crush it.
I have a feeling Mike is just putting us on....jeez. |
| papillon |
Posted - Feb 18 2007 : 16:00:49
Polar Skipper,
As the hands-down expert on this thread and whose expertise I have enjoyed reading immensely, I have just one question?
Are you able to fish through a hole in your cabin-floor year round? |
| Polar Skipper |
Posted - Feb 18 2007 : 15:50:01
Mike I'm not sure where you live but up here there is no hole - just solid ice and if there ever was a hole it froze over very quickly. Those open holes just freeze over and around and under whatever happens to be sitting there. I guess they never heard of Newton or Scientific Theory. Today is -28F and I'm not sure what the wind chill is but it feels nasty.
This exerpt is from the USA Dept of Energy website "When water freezes, it increases in volume about 9%. (this breaks thru-hulls-engine blocks-etc) The ice then shrinks as the temperature decreases. The shrinkage is tiny, about 0.4% going from +30F to -50F."
Because the shrinkage is miniscule it does not mean that you can count on your boat not sinking.
|
| John151 |
Posted - Feb 18 2007 : 15:50:00
While the other ROs bicker about the physics behind ice expansion, and others debate about the reason PMs require an anchor, I would like to point out that Russel's profile indicates that he lives in St. Louis, MO. While I don't have any experience with keeping boats in the water all year, I am inclined to think that the ice in the St. Louis region is not nearly as dangerous as the ice in the antarctic. This is probably why there are so many boats left in the water at his marina.
As you were..... |
| MIke F |
Posted - Feb 18 2007 : 15:12:55
Let me explain it another way--Draw a circle with magic marker on a sheet of ice at 32 F. Cool the ice to 0 F, The area inside the circle will get larger since the ice expands. Now cut out the circle (ice at 0 F). The circle will not shrink because you cut out the circle. The reason is that the ice inside the circle expanded to precisely fit the expanded circle. Now repeat the experiment with a sheet of ice at 32 F with a hole in it that is the size of the original circle--Just an empty hole. Cool the ice sheet to 0 F--the hole will get larger just as if the ice were in the hole. Now repeat the experiment at 32 F but a boat in the hole which just fits the hole. Cool to 0 F. The hole gets larger and as long as the boat does not expand as it gets colder, the hole will be larger than the boat. |
| papillon |
Posted - Feb 18 2007 : 15:05:38
Reminds me of the guy who called into the comedy show "Mr. Answer-Man" (or something like it) complaining that the small cabin he bought in Februrary on a northern lake was gone when he returned in April.
The fool was distraught that his new cabin, fully furnished, was gone. He was wondering how in the world he was going to be able to find another one where he could fish through a hole in the floor of his cabin. |
| papillon |
Posted - Feb 18 2007 : 14:58:21
Old Houseboater,
You're right on about water breaking a through-hull or unwinterized sea strainer. Not uncommon at all.
Ironic, isn't it, that if that should happen the only thing keeping your boat from sinking before the spring thaw might be the ice gripping the hull? |
| engdockter |
Posted - Feb 18 2007 : 14:50:49
I sure get a lot of different thearys about this but I asure you my slip wil be ice free next season, thanks for all your input |
| Polar Skipper |
Posted - Feb 18 2007 : 14:30:19
Living on the shore of Great Slave Lake in Canada's Northwest Territories I see a lot of ice - I also see boats that for whatever the reason were left to freeze in. Take my word for it the hole in the ice does not get bigger. It gets smaller at an alarming rate. If your boat has one side resting against an immovable object like thick shore ice the ice will first try to lift the hull as the freezing moves under the hull (our ice is 3 to 5 ft thick) and if the boat is a small aluminum fishing boat it will probably be OK half/half out of the ice. If your boat is too heavy for the ice to lift it a bit and relieve the pressure your hull is going to be crushed. This is why the early arctic explorers chopped the ice away from the ship sides when they wintered over in the Arctic Ocean.
I wouldn't worry about a few inches of ice other then it might scratch the gelcoat as the wind moves things around. |
| OLD HOUSEBOATER |
Posted - Feb 18 2007 : 14:21:44
The water can get in your thru hulls, expand and break them. A few sinkings occur every year from this problem when the water thaws. |
| bruceb |
Posted - Feb 18 2007 : 13:43:25
Mike F,
Your example has a flaw. If the hole actually got larger, that remaining hole would then also freeze expanding against the boat. |
| papillon |
Posted - Feb 18 2007 : 13:43:25
H2O expands as it freezes. This is why icebergs float rather than sink.
A boat will certainly contract a little when cold but not nearly as much as the ice surrounding the boat expands.
Rarely a boat will get crushed by the surrounding expanding ice. More often in our climate, however, the damage is from the boat constantly brushing against the ice when there is wind. Or when the wind slams the ice into the boat. This is why people remove their docks in northern lakes. The wind driven ice can destroy them. |
| MIke F |
Posted - Feb 18 2007 : 13:35:31
Rommer you are correct that the ice as a whole does expand (cracking and engine block eg) but a hole within the ice actually gets larger.
You can fill a bottle with water and fracture the bottle by freezing it but an empty bottle placed in water will not be crushed if the water freezes.
The empty volume within the water expands |
| MIke F |
Posted - Feb 18 2007 : 13:29:34
If a hole in metal gets larger as the metal expands, the hole in ice gets larger as the ice expands.
Think of it this way--suppose a boat made of solid ice albeit colored was placed in water and the water was allowed to freeze. The ice boat would not be crushed since it changes dimension exactly as the surrounding liquid. In fact it does not matter if the colored ice boat is there or not-- the hole would get larger just the same way Now replace the ice boat with a regular boat which will shrink as the vessel gets colder. |
| rommer |
Posted - Feb 18 2007 : 13:24:58
quote:
Originally posted by MIke F
Interestingly, a boat represents a hole in the water and when the water freezes, the hole gets larger not smaller. This is the same reasoning as applying heat to a strut to expand it and loosen a cutlass bearing.
Damage to a vessel occurs when the ice shifts.
Water is an oddity in nature in that it DOES actually expand as it freezes. Otherwise how would an engine block crack from freezing water?
|
| JeffR |
Posted - Feb 18 2007 : 13:01:59
Actually, heat expands material (metal in your case). As you heat something, say a nut or bearing, the material as a whole expands, and the nut or bearing loosens because the hole in the center gets larger. Water without doubt expands as it freezes and will try to close the hole, or in this case crush the boat. |
| MIke F |
Posted - Feb 18 2007 : 12:45:44
Interestingly, a boat represents a hole in the water and when the water freezes, the hole gets larger not smaller. This is the same reasoning as applying heat to a strut to expand it and loosen a cutlass bearing.
Damage to a vessel occurs when the ice shifts. |
| JeffR |
Posted - Feb 18 2007 : 11:09:46
OH! Haven't seen Bob posting lately...has he been politely escorted away?
BTW, I never said it was an attempt to get people to pay. I simply said it must be limited to those that have. |
| rommer |
Posted - Feb 18 2007 : 10:57:07
PLEASE do not think it is an attempt to get people to pony up!!!!
That is NOT the case.
If you really must know what happen you only need to ask one person. His actions have forced Les to restrict the use PM to anchored members only.
All together now, "Thanks BOB!"
|
| JeffR |
Posted - Feb 18 2007 : 10:47:08
eng...I just tried to get to mine based on your post, and I cannot. This must be a new update, limiting the folks that have not ponied up. I've always been able to send and receive pm's (extemely helpful on both accounts btw), but can't now. |
| engdockter |
Posted - Feb 18 2007 : 10:43:41
Jeff, how do I get to my pm it says I have a message but when I hit he pm box icon it takes me knowwhere |
| JeffR |
Posted - Feb 18 2007 : 10:33:25
Actually, Gary, us lowlifes can also send and receive PM's...unless something has changed very recently. (?) |
| engdockter |
Posted - Feb 18 2007 : 10:27:00
Thanks gary, thats what I figured, and yes I do like this site and will be joining today |
| The Other Gary |
Posted - Feb 18 2007 : 10:20:04
Guys, the PM function is available only to "anchors" as are several other features.
When you are comfortable with the site as to the advice and value here you may want to become an "anchor"
Click on the "help support this site" at the top of the page.
|
| engdockter |
Posted - Feb 18 2007 : 10:14:48
David Iam fairly new to this site and been trying to get to the pm for a while, unless it just dident come thriugh |
| cdstegall |
Posted - Feb 18 2007 : 09:30:21
Russel, you have a pm |
| engdockter |
Posted - Feb 17 2007 : 19:34:06
quote:
Originally posted by The Other Gary
Get a submersible sump pump, it does not have to be a high volume one for your area and hang it over one side of your boat about midships and say 3 feet down and plug it in. You only have to keep one side ice free to negate the force of the ice sheet.
The water it pushes up will open a large semi circle in no time. Do not break the ice away from the sides just make a hole and drop it down. use tie wraps to secure the cord to the line so that there is no pull on the cord.
Something like this HD item will work just fine as what it is really doing is creating a current that brings the warmer water from three or four feet down welling up to the surface.
Thank you gary. I think you are right on the money,it dosent freeze realy hard here but I think what you are sugesting will do the job
|
| The Other Gary |
Posted - Feb 17 2007 : 18:53:48
Get a submersible sump pump, it does not have to be a high volume one for your area and hang it over one side of your boat about midships and say 3 feet down and plug it in. You only have to keep one side ice free to negate the force of the ice sheet.
The water it pushes up will open a large semi circle in no time. Do not break the ice away from the sides just make a hole and drop it down. use tie wraps to secure the cord to the line so that there is no pull on the cord.
Something like this HD item will work just fine as what it is really doing is creating a current that brings the warmer water from three or four feet down welling up to the surface.
|
| CW |
Posted - Feb 17 2007 : 17:20:14
Water exerts 40 thousand pounds per square inch when it freezes. You do the math. |
| papillon |
Posted - Feb 17 2007 : 15:29:19
For several years, I've just dangled an inexpensive sump pump about 4 feet deep off the swim platform. It's been able to draw the relatively warmer deeper water up to keep the entire boat ice-free.
The most common ice damage to the hull is a rubbing away of the bottom paint not from an ice flow but from even gentle breezes.
Rarer hull damage can be significant. |
| engdockter |
Posted - Feb 17 2007 : 15:14:35
I agree with all of you ,I plan on a bubbler, hopfully no damage this year,I guess their are just a lot of lucky people around me because out of about 150 boats in our harbor like I say only about 10 percent have bubblers, this is my first year leaving a boat in water in winter weather, I do understand the thery of freezing and plan on a bubbler next year, thanks for all your feedback |
| Gregory S |
Posted - Feb 17 2007 : 14:44:47
There is no movement of the water in engine blocks that freeze and break either! |
-
