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Top heavy?
I've got an old boat very much like this one:
http://www.warnersdock.com/images/Fr...fores15yel.JPG that I'm trying to make into a mini-houseboat, sort of like a camper. I only expect to have about 200-300 pounds in the roof and walls, and the roof will only be about 48" above the gunwale. The hull will weigh a *lot* more than what is added, so shouldn't that alone be enough to keep it from being top heavy and flipping over? If I add weight, like a couple hundred pound bags of sand down in the hull to counterballance, shouldn't that take care of it? If so, should they be placed on the sides, or in the center? |
Top heavy?
On Jul 3, 11:34*am, David dh@. wrote:
I've got an old boat very much like this one: http://www.warnersdock.com/images/Fr...fores15yel.JPG that I'm trying to make into a mini-houseboat, sort of like a camper. I only expect to have about 200-300 pounds in the roof and walls, and the roof will only be about 48" above the gunwale. The hull will weigh a *lot* more than what is added, so shouldn't that alone be enough to keep it from being top heavy and flipping over? If I add weight, like a couple hundred pound bags of sand down in the hull to counterballance, shouldn't that take care of it? If so, should they be placed on the sides, or in the center? This is a bad idea on several levels. Even if you can make the math seem to work, the hull is designed to sit at a certain level in the water so as to be safe during all aspects of operation while cruising or in emergency conditions. Pitch a tent up there, or get a different boat. It's like pulling a trailer that is too heavy for the vehicle. The vehicle might get it rolling, but in an emergency can't react the way you want it to, or the way it was designed.. You might get away with it for years, but it could also get you killed in seconds. In a nutshell, you have the wrong tool for the job. Change your plan, or get a different boat... Just my opinion, but I am always against modifying a tried and tested design.. Scotty SmallBoats.com |
Top heavy?
On Thu, 03 Jul 2008 14:34:39 -0100, David dh@. wrote:
I've got an old boat very much like this one: http://www.warnersdock.com/images/Fr...fores15yel.JPG that I'm trying to make into a mini-houseboat, sort of like a camper. I only expect to have about 200-300 pounds in the roof and walls, and the roof will only be about 48" above the gunwale. The hull will weigh a *lot* more than what is added, so shouldn't that alone be enough to keep it from being top heavy and flipping over? If I add weight, like a couple hundred pound bags of sand down in the hull to counterballance, shouldn't that take care of it? If so, should they be placed on the sides, or in the center? That hull doesn't weigh as much as you think it does. Plus, it's essentially flat which, while counter-intuitive, makes it less stable. Alll boats and ships obey two laws of physics - center of buoyancy (CB) which is the center of the underwater volume of the vessel and center of gravity (CG) which is where all the mass would be concentrated if it had to be compressed to a single point. To float properly on the design waterline, then the CG must be in line vertically with the CB. Once you start messing around with CG (which is essentially what you are doing), it throws off the CB (because they are interrelated) and you are constantly playing catch-up to keep it properly oriented (dry side up and wet side down). Even adding 300 pounds isn't going to affect anything much because your CB, which is not a constant and can change depending on any number of factors, is out of whack. Additionally, you have to worry about beam - it ain't got none to speak of. You can figure it all out if you really want to. http://www.johnsboatstuff.com/Articles/estimati.htm Good luck. |
Top heavy?
On Jul 3, 4:23*pm, Gogarty wrote:
In article , says... On Jul 3, 11:34*am, David dh@. wrote: I've got an old boat very much like this one: http://www.warnersdock.com/images/Fr...fores15yel.JPG that I'm trying to make into a mini-houseboat, sort of like a camper. I only expect to have about 200-300 pounds in the roof and walls, and the roof will only be about 48" above the gunwale. The hull will weigh a *lot* more than what is added, so shouldn't that alone be enough to keep it from being top heavy and flipping over? If I add weight, like a couple hundred pound bags of sand down in the hull to counterballance, shouldn't that take care of it? If so, should they be placed on the sides, or in the center? This is a bad idea on several levels. Even if you can make the math seem to work, the hull is designed to sit at a certain level in the water so as to be safe during all aspects of operation while cruising or in emergency conditions. Pitch a tent up there, or get a different boat. It's like pulling a trailer that is too heavy for the vehicle. The vehicle might get it rolling, but in an emergency can't react the way you want it to, or the way it was designed.. You might get away with it for years, but it could also get you killed in seconds. In a nutshell, you have the wrong tool for the job. Change your plan, or get a different boat... Just my opinion, but I am always against modifying a tried and tested design.. Scotty SmallBoats.com It's not the weight. It's the moment.- Hide quoted text - - Show quoted text - I have programs here that will calculate any of it, but I was trying to keep it simple for a layman.. At the same time, a note to the OP... I defer to Eisboch in this case. He has much more experience than I in this area... I have booklearnin' he has boats;) |
Top heavy?
On Thu, 3 Jul 2008 16:30:25 -0400, "Eisboch" wrote:
"Gogarty" wrote in message ... In article , says... On Jul 3, 11:34 am, David dh@. wrote: I've got an old boat very much like this one: http://www.warnersdock.com/images/Fr...fores15yel.JPG that I'm trying to make into a mini-houseboat, sort of like a camper. I only expect to have about 200-300 pounds in the roof and walls, and the roof will only be about 48" above the gunwale. The hull will weigh a *lot* more than what is added, so shouldn't that alone be enough to keep it from being top heavy and flipping over? If I add weight, like a couple hundred pound bags of sand down in the hull to counterballance, shouldn't that take care of it? If so, should they be placed on the sides, or in the center? This is a bad idea on several levels. Even if you can make the math seem to work, the hull is designed to sit at a certain level in the water so as to be safe during all aspects of operation while cruising or in emergency conditions. Pitch a tent up there, or get a different boat. It's like pulling a trailer that is too heavy for the vehicle. The vehicle might get it rolling, but in an emergency can't react the way you want it to, or the way it was designed.. You might get away with it for years, but it could also get you killed in seconds. In a nutshell, you have the wrong tool for the job. Change your plan, or get a different boat... Just my opinion, but I am always against modifying a tried and tested design.. Scotty SmallBoats.com It's not the weight. It's the moment. I think it all depends on how the OP intends to use his "houseboat". 3-4 footers in the ocean? No way. A lazy, small lake somewhere? Go for it. Eisboch It is on a lake. I wouldn't try it in the ocean. It's not as wide as the houseboats around here, but it's not as tall either so I'm hoping it will sort of balance out and be about the same thing. And when I think about the cruisers in the ocean, with a flybridge, and then a flybridge on top of the flybridge, and sometimes a flybridge on top of the flybridge on top of the flybridge...how does all that work? |
Top heavy?
wrote in message ... I have programs here that will calculate any of it, but I was trying to keep it simple for a layman.. At the same time, a note to the OP... I defer to Eisboch in this case. He has much more experience than I in this area... I have booklearnin' he has boats;) -------------------------------- I have absolutely *no* experience in converting a small lake boat into a houseboat. Eisboch |
Top heavy?
Did I miss something here It's a POS sink it.
David wrote: I've got an old boat very much like this one: http://www.warnersdock.com/images/Fr...fores15yel.JPG that I'm trying to make into a mini-houseboat, sort of like a camper. I only expect to have about 200-300 pounds in the roof and walls, and the roof will only be about 48" above the gunwale. The hull will weigh a *lot* more than what is added, so shouldn't that alone be enough to keep it from being top heavy and flipping over? If I add weight, like a couple hundred pound bags of sand down in the hull to counterballance, shouldn't that take care of it? If so, should they be placed on the sides, or in the center? |
Top heavy?
On Jul 3, 5:01*pm, "Eisboch" wrote:
wrote in message ... I have programs here that will calculate any of it, but I was trying to keep it simple for a layman.. *At the same time, a note to the OP... I defer to Eisboch in this case. He has much more experience than I in this area... I have booklearnin' he has boats;) -------------------------------- I have absolutely *no* experience in converting a small lake boat into a houseboat. Eisboch Yes, but you have probably been in boats that size, or similar configuration.... I have not.. |
Top heavy?
On Jul 3, 5:12*pm, "
wrote: Did I miss something here It's a POS *sink it. David wrote: I've got an old boat very much like this one: http://www.warnersdock.com/images/Fr...fores15yel.JPG that I'm trying to make into a mini-houseboat, sort of like a camper. I only expect to have about 200-300 pounds in the roof and walls, and the roof will only be about 48" above the gunwale. The hull will weigh a *lot* more than what is added, so shouldn't that alone be enough to keep it from being top heavy and flipping over? If I add weight, like a couple hundred pound bags of sand down in the hull to counterballance, shouldn't that take care of it? If so, should they be placed on the sides, or in the center?- Hide quoted text - - Show quoted text - Yes, you missed the first line which suggests that this is not his boat, but one with a similar hull configuration..His boat could be spotless for all we know... |
Top heavy?
"David" dh@. wrote in message ... I've got an old boat very much like this one: http://www.warnersdock.com/images/Fr...fores15yel.JPG snip THIS is top-heavy: http://images.thebiggestbreasts.com/...fake_boobs.jpg Caution: nudity. Adults only please. -- Gregory Hall |
Top heavy?
On Thu, 03 Jul 2008 14:34:39 -0100, David dh@. wrote:
I've got an old boat very much like this one: http://www.warnersdock.com/images/Fr...fores15yel.JPG that I'm trying to make into a mini-houseboat, sort of like a camper. I only expect to have about 200-300 pounds in the roof and walls, and the roof will only be about 48" above the gunwale. The hull will weigh a *lot* more than what is added, so shouldn't that alone be enough to keep it from being top heavy and flipping over? If I add weight, like a couple hundred pound bags of sand down in the hull to counterballance, shouldn't that take care of it? If so, should they be placed on the sides, or in the center? Use a tent! The thing will add only 20lbs to the boat, is easy to remove, and can be configured all kinds of ways. Check LLBean for a tent that will fit. Put a couple thermarest mattresses on the deck and you're good to go. |
Top heavy?
Holy shi** g
--Mike "Gregory Hall" wrote in message ... "David" dh@. wrote in message ... I've got an old boat very much like this one: http://www.warnersdock.com/images/Fr...fores15yel.JPG snip THIS is top-heavy: http://images.thebiggestbreasts.com/...fake_boobs.jpg Caution: nudity. Adults only please. -- Gregory Hall |
Top heavy?
David,
Get a book on Naval Architecture and read about GM. Every boat has the center of gravity above the center of buoyancy. Weight added alone might not keep it upright. Matt Colie David wrote: I've got an old boat very much like this one: http://www.warnersdock.com/images/Fr...fores15yel.JPG that I'm trying to make into a mini-houseboat, sort of like a camper. I only expect to have about 200-300 pounds in the roof and walls, and the roof will only be about 48" above the gunwale. The hull will weigh a *lot* more than what is added, so shouldn't that alone be enough to keep it from being top heavy and flipping over? If I add weight, like a couple hundred pound bags of sand down in the hull to counterbalance, shouldn't that take care of it? If so, should they be placed on the sides, or in the center? |
Top heavy?
"Mike" wrote in message ... Holy shi** g --Mike "Gregory Hall" wrote in message ... "David" dh@. wrote in message ... I've got an old boat very much like this one: http://www.warnersdock.com/images/Fr...fores15yel.JPG snip THIS is top-heavy: http://images.thebiggestbreasts.com/...fake_boobs.jpg Caution: nudity. Adults only please. -- Gregory Hall LOL, is that a look of pain on her face |
Top heavy?
Mike wrote:
Holy shi** g Yes indeed! Amazing what they can with modern plastics ;-) THIS is top-heavy: http://images.thebiggestbreasts.com/...fake_boobs.jpg Caution: nudity. Adults only please. |
Top heavy?
David wrote:
I've got an old boat very much like this one: http://www.warnersdock.com/images/Fr...fores15yel.JPG that I'm trying to make into a mini-houseboat, sort of like a camper. I only expect to have about 200-300 pounds in the roof and walls, and the roof will only be about 48" above the gunwale. The hull will weigh a *lot* more than what is added, so shouldn't that alone be enough to keep it from being top heavy and flipping over? If I add weight, like a couple hundred pound bags of sand down in the hull to counterballance, shouldn't that take care of it? If so, should they be placed on the sides, or in the center? Well, boat stability is a complex subject. Here some loose thoughts (before my first cup of coffee, so no guarantees that I get all things right. I'm sure others will jump on the chance to correct my worst blunders - maybe I can learn something too!) I would recommend you read a bit more about it. The "Nature of Boats" by Dave Gerr is a good all-around introduction, and doesn't get too technical. Many other books work as well. When you add weight and windage high up, you reduce the stability. That increases the risk that your boat will capsize in high seas (or even in flat water). It also changes the way the boat rolls in seas, which may make it more or less comfortable to be inside. You are right, you can compensate by adding weight (as low as possible!). This will make the boat sit deeper in the water. Maybe too deep. It all depends what you are going to use the boat for. With a solid house on it, and enough ballast to keep her upright, she will not want to plane. If you can live with moving her at hull speed (a few knots), you can make do with *much* smaller engine, and use the weight difference as ballast. If you do not plan to move her around much at all, then you can afford to load he a bit deeper, as the sailing characteristics won't matter. You can probably get an idea of the stability by doing a simple roll period test. Rock the boat sideways, it will settle on some speed of rolling from side to side. If this roll time (in seconds) is the same as your overall beam (in meters), (or 10% more), you have what Gerr describes a good initial stability. If the boar rolls much faster, you have more (initial) stability for good comfort - that would be good news for you. If, after all the construction, your boat rolls slower than this, you may want to add some ballast. In any case, keep the structure as low as you can manage, and build it light! It looks like a small boat to begin with, so don't even try to build a large house on her. Keep it small and simple, and might work well. Remember that a boat is always a compromise. A heavily modified boat is a compromise between the original compromiseand a your new ideas. It is your own boat, and it is you who will have to live with it. Don't let us naysayers put you completely off. But watch out, it is also your own life you are risking, and possibly your dear ones as well! Good luck! -Heikki |
Top heavy?
Matt,
Haven't heard from you in a while. Nice to have you back. I remember that you knew my boat in her previous life. Take a look at her now http://home.maine.rr.com/rlma/Boat.htm Have you heard anything about the previous owners? Last I talked to them, one was having some medical issues and they weren't sure if they were going to be able to go cruising. I've now lost contact. Container ships sometimes have a slight negative GM, or used to 30 years ago when we would watch them come down the harbor with a slight list, make the turn, flop over, and continue on to sea with a slight list the other way. They have enough freeboard and flare in the ends that the righting arms would go positive after a couple degrees of heel. This loading made for minimal rolling and least strain on the upper layers of boxes. You can only get away with this in a very large ship though. The mini houseboat fellow won't get very far trying to apply what he reads about GM in a standard textbook to his problem. He should weight a sheet of plywood or get it's weight, calculate how much he needs to make the cabin, add about 50% for framing and other stuff, and then add the estimated weight of anything else he plans to put on board. Next put a table on board with the legs propped up a bit to get the top to about 75% of the cabin height. Pile the table with the estimated weight and go aboard. If the motion feels drunken and sluggish with very slow rools, the boat will probably be uncomfortable as well as dangerous. Keep removing weight from the table until a couple of people can walk around with the boat feeling solid and the rail getting close to the water. Then figure if he can build a cabin within that weight allowance. Strong winds are another issue but it sounds like this is a lake boat to spend most of its time on a mooring. -- Roger Long |
Top heavy?
Roger,
I like both your practical answer and your pictures. You're cruising my old stomping (sailing) ground. I do miss the coast. Tom had recovered well and was looking good last time I spoke to him. I'll send him the URL to your pictures. I was kind of hoping that this guy would get the plan that there is a whole lot to know before his question could be answered effectively. A tanker I was 2AE on had a negative GM and a slight port on the way out. Every wave made it snap to Stbd, stall a couple of seconds and snap back. It was all a guy could do to stay on his feet. We did lose the fire in one boiler, but the FM lit it off the bricks. My chief called the bridge and told them if they tried to make for sea this way, he would shut them down. - They believed him, but he still had to listen to a bunch of griping because we lost two hours while they finished correcting the ballast. Matt |
Top heavy?
On Jul 4, 10:46*am, Matt Colie wrote:
Roger, I like both your practical answer and your pictures. You're cruising my old stomping (sailing) ground. *I do miss the coast. Tom had recovered well and was looking good last time I spoke to him. I'll send him the URL to your pictures. I was kind of hoping that this guy would get the plan that there is a whole lot to know before his question could be answered effectively. A tanker I was 2AE on had a negative GM and a slight port on the way out. *Every wave made it snap to Stbd, stall a couple of seconds and snap back. *It was all a guy could do to stay on his feet. *We did lose the fire in one boiler, but the FM lit it off the bricks. *My chief called the bridge and told them if they tried to make for sea this way, he would shut them down. *- They believed him, but he still had to listen to a bunch of griping because we lost two hours while they finished correcting the ballast. Matt Well, at the risk of being simple. I still suggest it's the wrong boat for the job. He just needs to start with the right boat. He can justify, defend, and make any excuses he wants.. Still water, whatever.. But once you leave the dock, things can change quickly to something you have never seen before. Anyway. Have a great fourth, go out in your boats for me;) Scotty |
Top heavy?
On Thu, 03 Jul 2008 22:27:51 -0400, Matt Colie
wrote: Every boat has the center of gravity above the center of buoyancy. Why? Ever hear of heavy ballast keels? If the superstructure is heavy that's one thing, but it doesn't have to be. Casady |
Top heavy?
"Roger Long" wrote
The mini houseboat fellow won't get very far trying to apply what he reads about GM in a standard textbook to his problem. My guess from the OP's photo is that he has a tri-hull, of typical heavy 60s-style construction. If he goes through with his hard-top plan, I'm thinking he'll end up with something akin to a pontoon boat. |
Top heavy?
On Jul 4, 12:22*pm, "Ernest Scribbler"
wrote: "Roger Long" wrote The mini houseboat fellow won't get very far trying to apply what he reads about GM in a standard textbook to his problem. My guess from the OP's photo is that he has a tri-hull, of typical heavy 60s-style construction. If he goes through with his hard-top plan, I'm thinking he'll end up with something akin to a pontoon boat. Here is a neat program that will give you some pretty basic ideas of rightingmoments, bouyancy, trim, etc.. http://carlsondesign.com/#Fun_Shareware It's shareware, but for a quick idea of a design and it's capability, it is ok.. |
Top heavy?
On Jul 4, 7:52*am, wrote:
... Well, at the risk of being simple. I still suggest it's the wrong boat for the job. He just needs to start with the right boat. He can justify, defend, and make any excuses he wants.. Still water, whatever.. But once you leave the dock, things can change quickly to something you have never seen before. Anyway. Have a great fourth, go out in your boats for me;) Scotty It wouldn't surprise me in the least to find that the boat was originally sold in several configurations (eg. bow rider, 1/3 decked, cuddy cruiser, etc.). So, if the guy wants to convert from one to the other and enjoys doing the work the hull might well be adequate. Since we've only got a pic of the deck it is a little hard to tell what the hull form is, but given the bluff bow I'm guessing it's a Whaler style. If so, he's got oodles of stability. In Hawaii many small fishing boats have home built hard dodgers very like lobster boat style cabins. They put them on to get some cover when operating at sea and stability isn't typically an issue at all. If I were making this kind of conversion I'd put a little cuddy over the foredeck, build a hard dodger and run some rails off of that aft to use as supports for a Bimini, surfboard racks and tent. I'd probably also put a proper transom on the boat and build an external rack for the outboard. The cuddy and the transom will make the boat much less susceptible to swamping the result may be more seaworthy than the original. Sure he can do some testing to see if stability is going to be an issue. I like Roger's method and if he can secure the table and weights he can even go out and do some dynamic testing. But, in the end, I'd be amazed if a well constructed cuddy cabin would make the boat dangerously unstable. Happy 4th! -- Tom. |
Top heavy?
On 2008-07-03 11:34:39 -0400, David dh@. said:
I've got an old boat very much like this one: http://www.warnersdock.com/images/Fr...fores15yel.JPG that I'm trying to make into a mini-houseboat, sort of like a camper. I only expect to have about 200-300 pounds in the roof and walls, and the roof will only be about 48" above the gunwale. The hull will weigh a *lot* more than what is added, so shouldn't that alone be enough to keep it from being top heavy and flipping over? If I add weight, like a couple hundred pound bags of sand down in the hull to counterballance, shouldn't that take care of it? If so, should they be placed on the sides, or in the center? Judging from friends' boats of about that configuration, I'd suggest something quite a bit lighter: a light hard roof and tarps, screen and plastic for removable "walls", a pop-top camper of sorts. That said, a friend was for a time a "slum landlord" of a number of "floating structures" in Key West that were about what I hear you saying. They (mostly) stayed afloat for some years and weathered some nasty weather. Have to say that the inhabitants were not thought well of, though, and the "boats" uniformly disliked by all. Ugly doesn't begin to say it. -- Jere Lull Xan-à-Deux -- Tanzer 28 #4 out of Tolchester, MD Xan's pages: http://web.mac.com/jerelull/iWeb/Xan/ Our BVI trips & tips: http://homepage.mac.com/jerelull/BVI/ |
Top heavy?
Gregory Hall wrote:
"David" dh@. wrote in message ... I've got an old boat very much like this one: http://www.warnersdock.com/images/Fr...fores15yel.JPG snip THIS is top-heavy: http://images.thebiggestbreasts.com/...fake_boobs.jpg Caution: nudity. Adults only please. -- Gregory Hall WAFA will spend all week on that one. |
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