Towards "MY vs THE PERFECT BOAT"

Hi everybody. I'm new to this site. I was obsessed with the "concept/vision" of the "perfect boat"..( i still am)..but after starting a thread titled "THE PERFECT BOAT", seeking input /assistance on a forum on another site: (www.sailnet.com), and after interacting with all sorts of opinions and ideas, some of which were really very good, someone on that site advised me to visit this site for assistance. Just to summerize my objective, below is my first post on the thread, but if you think you could assist me i suggest you go thru all the posts to see how things evolved. I confess, i over-simplified things, and learnt a few things...however my obsession/vision still remains.

['The Perfect Boat' Hello everybody. I have recently discovered this forum/site after putting a search to help me gather ideas to build 'the perfect boat'. I was researching one criteria..and that was "unsinkable"..one of the results was one of the threads in this forum..which i found very informative..with inputs that reflect some higly professional comments..and thus encouraged me to subscribe and post this thread. This is probably too idealistic..but i believe it can be done.
What i'm trying to accomplish is not new and probably exists somewhere..but i have not been able to find it with ALL the criteria i wish toaccomplish in my "perfect boat". By the way, at this stage i'm limiting it to a 20-23 ft. power boat..with an outboard of about 40 hp..one that is mostly used by the majority of fishermen all over the world, and also recreational boats (with appropriate modification at a later stage if my efforts are successful).
The criteria are:
1. unsinkable.
2. selfrighting.
3. self-bailing.
4. has multiple means of propulsion.
5. affordable..
The main objective is to save lives all over the world..and hoping one day all..and i mean all boats whether sailboats, powerboats small or large will be built that way..similar to whats happening in other idustries..e.g. car air-bags are a must..etc..
Any ideas, thoughts, advice is appreciated. Actually anybody interested to join me in my quest is welcome.
Depending on the input, i will elaborate further on different issues].End of the post.
As i said it turns out that i over-simplified things, maybe ignarant to alot of things related to the initial objective, and trying to do a lot of things/changes all at once...so i decided to modify my approach. Instead of building a new boat /template/ and all the complicated logistics and expences that go along with it, i decided to go thru a "shortcut" and use my own boat to do the modification, to accomplish one criteria at a time. Off course if i could do it all at once with the aid of a sotware that allows you to design amd test via simulation, i would..but it seems too complicated and way above my head.

A breif description of my motor boat: Weight 2200 lbs, L24 ft, Beam 5.5 ft, Draft 16 inches, has 2 honda 4 stroke outboard engines 100hp each, and with all the expected weight (including the engines and passengers etc.. around 4000 lbs. When i bought it 16 years ago it was labeled as with "foam flotation"..(i always thought this ment that it was unsinkable. But after educating myself..it turns out that it only means that the boat would be just about level with the water and with one end only a few centimeters above the water.

To me,"unsinkable" is the first and most important criteria..and goes along with is "self-bailing"..then "self-righting"..then "multiple means of propulsion".

So my boat is out in the marina's workshop. I had the floor cut..underneath foam filled all the cavities..however it was soaked partially with water, and the dry parts when squeezed with my fingers would fragment like sand..some sort of a decaying process over the years.
I calculated how much lbs of bouyancy i would need and it came to be about 2500 lbs of lift..(4000\1.6).
I then calculated how much foam is need, and it comes to about 40 cubic feet..(2500\62).

After closing the floor again i intend to add another layer of foam and another "floor"..sort of a double deck..with drains to the sides..the objective being if the boat is swamped and fully covered with water , it would self drain gradually as i intend to make the "margin line" above the level of the side of the boat.
The problem is i have no idea how to calculate that!!..if i have no guidance i would probably test it by "trail and error" repeatedly, changing the variables untill i get it right..but thats why i'm posting this here, hoping to avoid that and any other serious mistakes.

Before i continue with how i intend to deal with the "self-righting" and "multiple means of propulsion" criteriae, please advise if i'm on the right track..and any advice would be appreciated.
Finally i would be interested if every one would define his/her perfect boat?

 

You idea for raising the floor above the load water line and providing scuppers for drainage is valid enough. That has been done in numerous designs. Problem is the boat will prefer floating in the inverted position if capsized. You may be able to fix that problem by adding a deep ballasted keel. If you add ballast you will have to add foam to offset the weight of the ballast, which will raise the height of the floors/scuppers. That level of design work is best done by someone very familiar with stability calculation.

For estimating you can use some simple numbers as follows. One cubic foot of foam will support 62.4 pounds of weight in fresh water or 64 pounds in salt water. You must include the weight of the foam while tinkering with the arithmetic. Example; When using 5 pound/cubic foot foam, subtract 5 from the 62.4 or 64 pound figures. If you are measuring in inches, use 0.0361 pounds per cubic inch for fresh water or 0.0370 for salt water.

If you succede in designing a boat to fulfil all five of your objectives you will be hailed as one of the foremost geniuses of all time. Number five is the kicker. You have seen that foam is not permanent, and not totally water proof. Foam cored boats gain weight over time and you must anticipate that fact in your calculations. Part of the "affordable" requirement must include amortization for limited life span.

 

messabout,
Thanks for your input.
Regarding what you mentioned in your first paragraph has to do with "self-righting" criteria, which i did not want to bring up untill i dealt with th "unsinkabe" and ""self-bailing" critrtia.
My plan regarding self-righting is to use the stainless steel bars i have infront and the back of the boat ,that are currently supporting a light bimini-type of sun-shade. I will remove the bimini and use some sort of durable fenders of appropriate design (flat type),well secured to the s/s poles. I will ensure that the poles themselves are well secured to the body of the boat (bolts). So the whole thing looks like a bridge..a "bouyant bridge". So now if the boat is capsized, these will ensure righting it. Like you said , there will be enought ballast at the bottom, more along the middle third of the boat (near its center of gravity)...again i will need to test things in real life and see if it works. Another thing i am considering of doing either alone or in combination with the above "bouyant bridge". And this is to add on top of the the existing forward small cabin an air-tight fiberglass compartment filled with foam...this if desiged to give a spherical shape (in cross-secto\ion), will hopefully ensure self-righting.
Balancing things is important, so that the action of self-righting should be slow enough to enable passengers hang on to the boat as it self- rights itself.
I wish someone could tell me how much of each i should use i.e. bouyancy vs ballast to make all this happen. And again, testing it in a real life simulated situation will help decide what to do next.
So again..am i on the right track?..any advice?

 

I'm no naval architect, but bearing in mind this is a 20-23 ft. power boat, how on earth would someone accomplish number 2 (selfrightening)?

Second, I wonder what you mean by "multiple means of propulsion"? Do you mean electric, diesel, hydrogen (a carrier), and gasoline? Or do you mean sails (= a mast, perhaps a keel etc), oars and so forth?

I don't get it. To me it seems as if you want a bike you can carry up the stairs, but at the same time you want a motorcycle and a van. Oh, and you want it to be amfibian at the same time. Okay, that might be a bit over the top when comparing, but it seems as some of those things are mutually excluding.

 

Hmm, I can't help but think of the life boats on big ferries. They have a hardtop, and that makes them selfrighting (with ballast, of course).

 

==="The criteria are:
1. unsinkable.
2. selfrighting.
3. self-bailing.
4. has multiple means of propulsion.
5. affordable..
The main objective is to save lives all over the world.."======
You have oposing criteria. some requirments will work together, but then adding another will cancel a previous one. To acheive the total demands would result in an expensive wildeabeast of a boat that your target user group could'nt use in "their" specific needs.
There will never be a uniboat, a cookie cutter craft that we ALL pull off the shelf & use to pursue our work or recreation on the water.
The USCG training boats used at the mouth of the Columbia River are self righting/unsinkable. Not sure but I think not self bailing nor cheap. I don't want to shrimp or crab from one.
I admire your humanity and goal, but we can only help with parts that will never fit together. You will have to remove a few things on that list if you want a real boat.
We can , however "dream" with you, that's fun to do.

 

==="The criteria are:
1. unsinkable.
2. selfrighting.
3. self-bailing.
4. has multiple means of propulsion.
5. affordable..


I think all those criteria were met by the very first boat, The LOG.

(sorry...just couldn't resist)

 

You will have to have enough foam to equal the displacement of the boat plus the amount of the water that will fill the areas that will trap water temporarily while draining. In other words you will have to make the areas where the water will pool while draining small enough that the weight of the water wont push the boat down enough to cover the scuppers and drain holes...so the enclosed water will be able to get out. You will have to replace the volume available to water with foam... or sealed chambers. Don't forget...all this foam makes for no place to store anything.
In a nutshell...the weight of the volume of water that can be trapped for any length of time cannot cause the boat to exceed the displacement at which the drainage holes are placed...else it won't drain. It doesn't really matter if there is foam filling the other space or it is in a useable sealable space form.

Steve

 

And....., remember also, unless this foam is polystyrene (which can't be "poured" into cavities), you will be designing a big water logged sponge.
Much better to design watertite compartments, low center of gravity and heavy ballist keel.
A boat like that, WITH a great sealed chamber above the cockpit or cabin would be selfrigting & as unsinkable as practical.
Urethane foam is the first material I would throw out the window. Bad foam, bad foam, get!

 

Ted655 is probably on the right track. "low center of gravity, watertight compartment, etc".

There are some features of the bouyant roof idea that could prove troublesome. The roof or top flotation chamber has sufficient displacement to prevent the boat from inverting. The boat has been knocked down. The center of bouyancy will have moved outward away from the boat. The boat is now a sort of catamaran. The boat will want to lie in the water on its side. It will be very difficult to right the boat. The weight of the top bouyant structure is like a big lever with a weight on the end of it. You will need a lot of ballast to overcome the weight at the end of the lever and the ballast must be far enough away from the center of gravity of the sideways boat to cause it to right itself.

Generally speaking, top hamper or weight aloft is a bad idea. Any structure that places weight above the center of bouyancy is detrimental to the safe operation of the boat. Weight aloft sets up a moment arm that exagerates the rolling and pitching of the boat. Simplisticly, it will slow the rate of roll, but it will roll farther. Long slow rolls are very uncomfortable to most people. Comfort is not one of the criteria that you have proposed but it is worth serious consideration.

If you can get your hands on the plans and commentary of Phil Bolgers' Birdwatcher design, you will come to understand what Ted has mentioned: ballast and high flotation (but not too high). Birdwatcher does not use lead or other artificial weight. Bolger merely makes the boat bottom brutally thick, strong, and resultantly heavy. That puts the weight where it will do the most good while giving the boat the ability to withstand severe abuse to it's bottom. O.K. Birdwatcher is a weird looking boat but it does almost all the things that you have outlined, including multiple means of propulsion.

 

"The life boat was created back in 1784 in England by a coach-builder named Lionel Lukin. He was obsessed by the fact that when a ship got in trouble out on the seas, the crew and passengers would take to the small boats carried aboard to escape the sinking or burning vessel, only to lose their lives in the small boat when it would overturn or sink in rough weather. He redesigned a 20-foot Norwegian yawl he obtained, by installing water-tight chambers filled with cork in the double-ended (pointed) bow and stern. He then installed a heavy cast iron keel to make it right itself if it would turn over in heavy seas. He then installed a deck inside with holes (scuppers) on the sides above the water line. This would make it self-bailing. He called it an "unimmersible" and named it The Experiment. His concept was successful and the true life boat was born." The Motor Lifeboat, Donald L. Nelson

"Much better to design watertite compartments, low center of gravity and heavy ballist keel." ted655

Ted's on the right track, definitely. That principle of design has been the basis for self righting lifeboats in the UK and US for more than 200 years, as well as the current generation of SOLAS approved lifeboats on oceangoing ships, as Danish Bagger pointed out. It's a pretty good track record. Donald Nelson was a USCG lifeboat crewman for much of his life. He died in 2006, but his website has a wealth of information on what made these lifeboats so successful at surviving incredibly rough seas: http://www.pasty.com/~barbspage/MLB.HTML#MotorLifeBoat

As others have said, no one boat can be best for all purposes. You have to prioritize your requirements. Unfortunately, #5 usually suffers if the first 4 are met, but it doesn't have to disappear completely. The most recent 44' and 47' USCG lifeboats have become much more complicated and costly because they have been built for even more requirements, including high speed and larger cabin space for survivors. The earlier generations of lifeboats, as described in Donald Nelson's website were much simpler but very rugged. A design incorporating their features should do most of what you want.

Good luck,

Charlie

 

perhaps ,,you may want to look at J,C boats of new england,,,the 31 ftr,was made of airex,,which is supposed to be stronger and lighter than fiberglass ..and floats,,our boat also had 13 airtight compartments .blown with foam,,a self bal=iling deck ,,and 2 210 hp volvos ,,driving duoprop outdrives,,,,,and a keel ,,,about 4 ft 11 inch draft ,with some ballast the engines were at the stearn in thier own compartment ,,also self bailing. too boot ,,she had a 6000 lb paylaod at the center of gravity plus one ton , ( of fishing gear)I can personnaly say ,, I rode many ,many tropical depressions and 4 hurricans out ,,in this boat,,,and was able to retrive 20 miles of sword fish gear in winds steady at 70 knots gusting to 120 knots,,,buy the way the 31 jc is a semi displacmen semi planing hull ,,with a 6000 lb payload in 3 to 5 seas and the duo props you could do 20 knots and burn one gallon an hr,some will find this hard to believe ,,look in old national fisherman magazins 1980 to 1989,,,,3 of these yrs the fishing vessal broadbill highlined the gulf of mexico ,,averaging 200,000lbs of grouper and swordfish per year ,,,,,,,,longliner

 

Longliner, you sure you remember 1 gph in a heavily loaded 31' commercial boat @ 20 knots?? Maybe one mile per gallon (which would be damn good)?

Charlie

 

no ,,this is one gallon per hr in slick calm ,,,,,2 gallons in 3 to 5,,..twin tubocharged volvos..,we had speed props and tractor props for full load ,,the duo props have little cavitation ,,all force is used to propel the boat ,, there is ,,or was 5 of these boats in the gulf ,,the touche' ,,the miss lila ,, the broadbill and broadbill 2,,and the kantoo,,,,,,I am really surprised that this set up didnt get more attention,...like I said ,its all been documented in national fisherman mag in the 80s,,,besides in my life ,,too much crap happens ,,,,,you cant make this stuff up ,,,,,,longliner,,,,,try googaling 31 jc boats,,,,,,,I find info but cant get it back up