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Old 12-02-2012, 04:19 PM   #21
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I'm thinking that a well balasted keel, would make for quite a long righting arm, and make the boat more stable.

Be careful with that idea.....it might be good up to a point. If you add ballast to a boat not intended to have it, she will float deeper in the water. This means the rail goes under water sooner as she heels, which could cause early flooding at a lower heel angle. Usually peak stability is just as the rail (deck edge) goes under water.

Yes, adding ballast to lower G is increasing stability, but whether the lower capsize angle is worth it is a question.....
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Old 12-02-2012, 05:01 PM   #22
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Most designs that are narrow it seems are priority wise leaning toward more efficiency and weight even for a full disp hull is of great importance. The most common rule of thumb for determining the amount of power required for a disp hull is weight/power. More or less directly proportional. So we see most narrow boats built low w little top hamper.

So ballast has it's price.
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Old 12-02-2012, 05:39 PM   #23
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I'm thinking that a well balasted keel, would make for quite a long righting arm, and make the boat more stable.

Yes but thats another part of the equation that was taken into consideration when the center of gravity was calculated right?

oh, and veyr nice boat
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Old 12-05-2012, 11:20 AM   #24
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First thanks Tad, That was very help full. I did a little more looking but you got me in the right spot to look. And the right frame of mind too. For some reason when i made this post i was looking at the boats for sale. When I found the off shore "race boats" the 100mph or +, 2 and 3 engine boats and some of them are very long even 38 to 40 ft but only 11 feet wide. ....... I know just because it fits on a trailer and its a boat. its not the same lol I do understand but just got the wheels turning upstairs a bit.

Until i retire the only way i can justify a trawler or any other boat is I have to be able to put it on a trailer I can pull with a 1 ton truck. One of the down sides to living in the middle of the USA in Missouri.

Thanks again guys.
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Old 12-05-2012, 10:02 PM   #25
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First thanks Tad, That was very help full. I did a little more looking but you got me in the right spot to look. And the right frame of mind too. For some reason when i made this post i was looking at the boats for sale. When I found the off shore "race boats" the 100mph or +, 2 and 3 engine boats and some of them are very long even 38 to 40 ft but only 11 feet wide. ....... I know just because it fits on a trailer and its a boat. its not the same lol I do understand but just got the wheels turning upstairs a bit.

Until i retire the only way i can justify a trawler or any other boat is I have to be able to put it on a trailer I can pull with a 1 ton truck. One of the down sides to living in the middle of the USA in Missouri.

Thanks again guys.
I don't think it takes much to get a permit to go over nine feet wide. I know in California it dosent
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Old 12-05-2012, 10:44 PM   #26
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Eric
As to the Alaska Ferries being extended and gaining speed. Yes, As I recall, the extension increased speed by almost a full knot at original setting.
In conversation with a now decested old tug boat master who knew engineers on the ferries, the increase in hull speed allowed the ferries to reduce RPM allowing maintaing the schedule speed (Fexablility when required, like making up for lost time during incidents) This was during the 70's fuel crunch when saving fuel was a factor. The Malaspina on the Bellingham run saved tons of fuel on each voyage. I believe that system was then running PS300 Lt Fuel (actually heavy fuel, but did not require quite the heat to make it flow from the tank to engine) Currently the system is running pure diesel.

Tad- On a earlier thread, I had opened a discussion on ballast as it related to vessel rolling. You echoed knowledgeable posters with your diagram and explanation. The conclusion of that discussion has me convinced to add ballast. The situation is locating ballast at a palatable cost. I have discarded the thought of using 60# bags of cement/sand mix (contained within plastic garbage bags till atmospheric moisture set them hard) and now am budgeting for 60# commercial lead cannon ball trolling weights. (almost $2.00 per #) How many? Darn'ed if I know, just keep adding till results are gained!
Thanks for the refresher.

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Old 12-06-2012, 07:03 AM   #27
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For most trailering folks staying under 8ft 6 ,no permits, is the easy solution.

An allowed 40 ft trailer length will allow a pretty large boat , but many states limit the overall length of the combination to 65ft. A few are at 75 , a few in the NE are 55.

YES ,commercial trucks go way longer , but non commercial IS limited.

For our use we built up a 35 ft bus conversion (reinforced frame , 400hp engine) and the trailer LOA limit caused us to select a 23 ft boat , remember the fuzz will be tape measuring to the end of the tilted up out-drive.

There is also some space required at the trailer ball end to be able to go round corners.

As it is impossible to back a trailer that can not be seen, the simple solution is a front mounted ball hitch , that makes launch recovery a snap.

Works on cars and trucks too!
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Old 12-06-2012, 11:58 AM   #28
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How come all the trailer able boats that have a 9 foot to 10 beam are under 28 foot. Why don't they make a 32 to 36 foot long boat that is only 9 ft wide? I would think you could add a few feet to the length and have a very cool trailer able boat.
Why don't 'they' make long narrow trailerable boats?
It's not a question of stability or seakeeping or performance, it's because nobody would buy them. Side by side not one American in a million would pick the skinny boat, especially if his wife and kids had anything to say about it.

Things are different elsewhere.
Narrow boats for sale, Canal boats for sale, narrowboats
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Old 12-06-2012, 12:13 PM   #29
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Jeff,
Boats were narrow in the past mostly because they were easily driven when narrow and high power engines were not available. It's hard for me to believe most all boats are still wide (including my own) the way people complain about fuel consumption. And people don't like "tippy" boats ... even yachtsmen. Don't see any narrow inflatables. Actually I think there is one that is fairly narrow but I've never seen one.

But if your'e happy at 6 knots wide can be driven quite easily too ... almost as easily as narrow. And if my own Willy were widened to 12' beam my present engine would not need replacing and for all practical purposes Willy's not overpowered.

But if you get even close to hull speed narrow = easily driven.
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Old 12-06-2012, 12:20 PM   #30
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Tad- On a earlier thread, I had opened a discussion on ballast as it related to vessel rolling. You echoed knowledgeable posters with your diagram and explanation. The conclusion of that discussion has me convinced to add ballast. The situation is locating ballast at a palatable cost. I have discarded the thought of using 60# bags of cement/sand mix (contained within plastic garbage bags till atmospheric moisture set them hard) and now am budgeting for 60# commercial lead cannon ball trolling weights. (almost $2.00 per #) How many? Darn'ed if I know, just keep adding till results are gained!
Thanks for the refresher.

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I don't suppose you have a foundry up there? Pig iron is about the cheapest/densest thing currently (bought at retail prices) available. Common cement bricks from the building supply (not hollow ones) will work if you have space. Steel flat bar cut into sections and painted with Primacon will stow nicely. The advantage with using steel is that it's easy to drill and bolt down. Here we have a recycler that will sell scrap lead (not perfectly clean) for about a dollar a pound.....

Whatever you use make sure it absolutely cannot move even if the boat is upside down.....
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Old 12-06-2012, 03:37 PM   #31
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Jeff,
Boats were narrow in the past mostly because they were easily driven when narrow and high power engines were not available. It's hard for me to believe most all boats are still wide (including my own) the way people complain about fuel consumption. And people don't like "tippy" boats ... even yachtsmen. Don't see any narrow inflatables. Actually I think there is one that is fairly narrow but I've never seen one.

But if your'e happy at 6 knots wide can be driven quite easily too ... almost as easily as narrow. And if my own Willy were widened to 12' beam my present engine would not need replacing and for all practical purposes Willy's not overpowered.

But if you get even close to hull speed narrow = easily driven.
I wonder what would happen to get hit on the beam with a large wave in a 8.5 foot wide 40 foot boat?
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Old 12-06-2012, 04:33 PM   #32
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bfloyd4445,

I'll answer your question w another question since the situation you presented is vague. Light boat heavy boat high CG low CG wct ect ect. But I'm sure the answer to your question would have more to do w hull shape and CG than beam.

If there was an 18' canoe w a 40" beam and a stretched version of the same boat that was 36' long and someone asked you to stand on the gunnel of one of them which one would you choose to stand on?
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Old 12-06-2012, 04:38 PM   #33
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I wonder what would happen to get hit on the beam with a large wave in a 8.5 foot wide 40 foot boat?
First of all what's a "large wave"? Is it 3' high or 16' high?

Capsize studies in wave tanks have shown that, if a vessel is laying beam to the sea, a wave with a height (trough to crest) approximately 30% of her length will roll some vessels some of the time. With waves of 60% vessel length, all (of the models tested) will roll every time. So, in theory, a wave of 24' will roll your 40' boat. But much depends on frequency (crest to crest) or steepness of the waves. I've been in huge waves in the open Pacific but the crests were 1/2 a mile apart.....not really steep enough to capsize anything.

I've studied this a fair bit. And the reality is that few recreational boats are lost in North America due to capsize in waves. Most often capsize is due to loads shifting or downflooding......The motor quits and a wave comes over the stern, a combination of downflooding and free surface effect.
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Old 12-06-2012, 05:00 PM   #34
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bfloyd4445,

I'll answer your question w another question since the situation you presented is vague. Light boat heavy boat high CG low CG wct ect ect. But I'm sure the answer to your question would have more to do w hull shape and CG than beam.

If there was an 18' canoe w a 40" beam and a stretched version of the same boat that was 36' long and someone asked you to stand on the gunnel of one of them which one would you choose to stand on?
the 36' one of course......hummmm, i think i see what your getting at. I'm useing my experiance in narrow beamed boats which tended to be very tippy compared to the same lenght style boat with wider beam. Even though a wider beam will not be affected as much by large loads shifted to port or starboard stability in a heavy sea may in fact be superior with the narrow beam. There would be less surface area for the breaking wave to impact on a longer vessel with narroe beam.
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Old 12-06-2012, 06:09 PM   #35
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TAD wrote;
"The motor quits and a wave comes over the stern" No big surprise here as many boats look more like a Jacuzzi or a hot tub than a boat in the stern.

Also,
"And the reality is that few recreational boats are lost in North America due to capsize in waves" No surprise here either as almost all boats are wide. And beam = stability .. all other things being equal. And of course they never are but people think they KNOW wide is stable and safe and narrow will tip over. So people buy wide boats w lots of power .. power for safety of course.

Very interesting about the % of length capsize studies. As stated it says the longer a vessel is the less likely it will capsize from a given wave (in height).
Well Tad I'll be watch'in out for those 17' waves while out in my 30' boat. Only been in those once and I was in an 28' OB that I designed and built. Mus'ta done someth'in right as I'm still here. Actually I'll be watch'in out for for those 9 footers too. AND I'll be hang'in on white knuckl'ed to the helm also.
Does the % of length "rule" or findings take into consideration the CG change over long boats and short boats that are all the same size ... volume/disp ? Or are all the hypothetical short and long boats all the same beam? Or have I read this all wrong?
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Old 12-06-2012, 06:30 PM   #36
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I think the percentage of boat length to wave height was based on a boat laying dead still in a beam sea Eric. The percentage would not apply to a vessel making headway. I may be confusing it though too.
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Old 12-06-2012, 06:46 PM   #37
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and now am budgeting for 60# commercial lead cannon ball trolling weights. (almost $2.00 per #)
You can do what I do down in Missouri. Call around and find a recycle place and ask them if they will sell the scrap they take in. I got a local scrap yard that well sell lead to me at 0.75 cents a LB. We buy if for Scuba dive weights and fishing weights. Take and old cast iron skillet and fish cooker add your favorite drink and a little time, it won't take you long to get all the weight you need. scrap iron is 0.35 a LB. I picked up 10 ft of rail road track that weights about 90lb a foot, I have cut it up use it from time to time as weight for the tractor implements. We got a lot of guys in this area that race stock cars and they use big blocks of lead weight to off set the CG of the car you just need a few of them to melt down.
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Old 12-06-2012, 07:02 PM   #38
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wow them are skinny boats, its like the one guy said before no wife or kids would ride in that after seeing the wider boats.

I have looked for boats like yours in your pic and can't find any when searching... got any tips on how you find one like yours. would you have any pics of the inside lay out? i could look at.
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Old 12-06-2012, 09:52 PM   #39
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Water Rescure- Hummm. Living on an island far away from trains and no scrap yards, leaves me with the trolling leads to this point. Even though the cost is high, one can purchase one at a time. Placing them in bread baking pans will contain them. The other thought was using used zincs from commercial boats. The yard piles them up on removal and eventually they will ship 55 gallon drums of these south. I suppose they would melt easy enough, in your suggested fry pan. Thoughts? AMJ
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Old 12-06-2012, 10:03 PM   #40
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your suggested fry pan. Thoughts? AMJ
Plumbers used to melt lead in cast iron kettles, no reason a pan wouldn't work fine too.
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