flat bottom hulls

According to Loveofsea both Ragtime and Infidel are inherently flawed designs, likely endangering it's crew, making Spencer liable. Your designs are also inherently flawed too Tom (mine also according to him) and now that you know this, you should be held liable for negligence at the very least or depraved indifference or manslaughter in the event of a tragedy. Of course, Loveofsea is the only person on the face of the earth that knows why and refuses to explain or qualify these accusations, but lets just permit him to run his mouth some more shall we.

 

There are many configurations of flat bottomed boats . Differing amounts of rocker and flair , beam to length ratio ,as well as fore and aft buoyancy. Ballasting and keel make a difference also . Am I confused , or not getting the
argument ?

Frank

 

From what I can get from the original posters intent, was why people say English canal boats, with flat bottoms and straight sides, are not safe at sea. He finally asked..

Flared sides give more ultimate stability, and you can maneuver a small flat bottom skiff like a dirt bike, but the guy isn't going to build a canal boat with flare and he certainly isn't going to dart from crest to crest and surf down the face of the waves in a 7' wide, 60' long canal boat.

The OP mentions people that have done this and that, but that means nothing. If you pick the right conditions, it can be done. But, like Chris Rock says "Just because a thing can be done, doesn't mean you ought to do it. You can steer a car with your feet, but that doesn't make it a good ******* idea."

Two things you should take into consideration when thinking about "safe to use at sea", changing weather conditions while at sea or loss of power and/or steering.

This is the question...

 

Curves, and particularly compound curves, increase the stiffness of a shell. It also avoids stress concentrations along a sharp chine. So curves certainly have a structural advantage.

Using light cored sandwich panels it is possible to make panels of high stiffness for weight. Joining the panels along the chine can be done with a heavier layup to reduce the material stress at the chine. So a one-off boat using stitch and glue type construction can be almost as structurally efficient as a curvy hull. Maybe even equal or better if the consistency of the flat panel construction is taken into account compared with other methods such as moulding.

If you look closely at the photo of the LCS I linked earlier you will see that the main hull has close to a flat bottom beamwise but it has a tight radius plate at the chine rather than a welded seam at the chine. This gets the weld away from the high stress point and the stress is lower due to the radius. Same thing is done on cargo ships. These would need heavier plating to achieve the same structural strength if the weld was along the chine.

Rick W

 

Sam Sam,

I think the question has been answered adequately for the limited nature of the question. It should be clear that there are many different forms of "flat bottom" boats and that some are safe offshore and some are not. The canal boats mentioned fit firmly in the former unsafe category.

One thing has bothered me about Ragtime/Infidel (same boat with different names). It was very successful and won a major offshore race in record time as late as 2008. Infidel (later Ragtime) was launched in the 1960's and won the extremely tough Sydney Hobart race and then the TransPac. That is a 40 year span of winning races although some modifications did take place over the years. Is there any other design that can come close to that record?

My question is, with only one hard chine plywood boat having all this success, why have others not tried this path? The boat has always been looked down on by some as being a cheap aberration and held in the same regard as multihulls by some.

 

I didn't want to have to do this PAR but you left me no choice. Since you chose to drop a dime on your cohorts Spencer and Tom, I'm going to have to insist that the three of you turn yourselves in to the authorities. Get your affairs in order gentlemen, you have until Monday morning at precisely 9AM to surrender. If you chose to flee from justice, the three of you will be pursued to the far corners of the earth for your crimes against humanity!

Watch this video:

http://www.youtube.com/watch?v=AFY9x5YBft8&feature=related

The kid that was thrown overboard will be the prosecution's chief witness.

 

Unless you look at the hull forms in some objective manner in their entirety there is a firm belief that curves have to perform better because they are more common and more difficult to build.

In my view there are two common beliefs that lead to the conclusion:
1. If you look at a hull section it is quite easy to determine that a semicircular section will result in the smallest perimeter for the maximum enclosed area. This leads to the conclusion that a rounded hull will provide lower wetter surface for a given displacement than a form with a rectangular section.

2. Water will not maintain streamline flow around a hard chine so there will be increased drag with a hard chine.

These conclusions are grounded in fact but they are simplistic and only look at elements, not the whole boat. Once you start to consider wave making, lift, sinkage and trim the flat bottom hull has an advantage.

I have discussed the merits of flat bottom rowing shells with Leo Lazauskas as it is an area he has worked in and he believes the weight shifting that goes on in a rowing shell, causing pitching motion, would disadvantage the hard chine. From my experience with pedal powered hulls, where the thrust is even with little weight shifting, the flat bottom performs better than rounded. You could expect the same with a sailing boat. In fact the hard chine will act to dampen pitching and roll so could be a significant advantage.

When designed I expected the hard chine hull to have similar performance to the rounded chine because I could build it lighter but it has proven to be a faster hull. The weight reduction does not explain all the advantage. The improved lift with the flat bottom is noticeable.

Rick W

 

http://www.youtube.com/watch?v=IPoAOXf8RIo&NR=1

 

Great video Frank!

i can almost guarantee you that there was a welder or metal fitter who was running around telling them that they had a big problem here--

and the professionals were in complete denial..

sorta reminds me of somone....

 

Yes........

to give you the answer you have a right to get here! (and had already to wait too long)

All commercial freighters are nothing but that! And James Cook was a good hint.
Not the worst performers in coastal waters are the Dutch flat bottomed boats (some even crossed the oceans, which I personally would not do, but I´m a chicken, or so)


The..."it depends" section was more or less successfully described already. Though you should forget the "love of sofa" drivel.


NO........

if it is a canal cruiser, definetively not, and under no conditions. Only a complete insane person goes to sea in a "narrow boat".

Regards
Richard

 

Yep, another "inherent design flaw", you clueless *** . . . I will ride you like a cheap hooker. You can't even explain why that happened (that old video is well documented folks), let alone your own assertions that have me pissed at you. Explain why everyone except you (naturally) is wrong Loveofsea, or this will continue.

 

http://www.angermgmt.com/

 

I don't need anger management. I one of the calmest, coolest persons you can imagine. I just find it outrageous that you can insult and insinuate, then suggest your design skills are the only real answers to your stated objections with everyone else's work. Yet, you don't offer any details, explanations or data to back up your argument, nothing and just leave us hanging with the insults and accusations. I've repeatedly proven my worth an will be damned if friends, co-contributors, customers, clients and potential customers or clients will have to hear your line of rhetoric, without some justification and qualification of your accusations. You intentionally stirred up a hornet's nest and now can't possibly ***** about getting stung. You know what the solution is, so you can toss your penny in the kitty or sit on the sidelines and watch.

 

You have a quite impressive way of making friends!

I seriously doubt you ever have been in severe conditions at sea!

I seriously doubt you ever have designed a seagoing boat.

I seriously doubt you ever have built a seagoing boat.

I seriously doubt you ever have encountered true professionals in boat design / boat building.

I seriously doubt you ever have made it to a higher level than 5 grade.

Providing links to a knitting circle (fits your attitudes), does not replace your obligation to deliver proof of your insane statements!

You are a well proven unprofessional, a idiot, or ***** (choose the appropriate when you meet your esoteric circle next week).

Get it to a valid statement what you have stated here or keep your dumb, dull and inexperienced mouth shut while adults are talking business!

edit:
sorry Paul, thought it was a direct reply, was too slow typing. Bloody Huns, must get it flawless before sending, that slows down.

Richard

 

The whole thing just kicks me in the *** Richard. I survived a combat tour with a few Purple Hearts, I rode an ambulance in a major city, have seen and done more then most, but I'll be damned if I can do it right. I've just shipped out a set of plans, just two days ago, to a nice fellow in Tasmania of all places and yet, it's fundamentally flawed. I designed it for the deep water and the particularly nasty conditions down there. I did a good bit of research on the prevailings, etc., but I'm just wrong I guess. It would be nice to know how, but this puddle duck apparently has a patent lock on things and is keeping it to himself, one would suppose. Clearly one as "in touch" with humanity as he claims, wouldn't be keeping his life saving discoveries and revelations to himself.