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Discussion Starter #21
CD,

Thanks for our honesty.

Do you have any knowledge of how the new Beneteau 40 measures up? We are thinking about the new 40 not the new 43 as it would be out of our price range, but I am interested in what you may know of the new 40 design relative to the points you brought up.
 

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Daniel,

Most of the "oil-canning" that I've heard described has occurred below or near the waterline, usually on flatter hull sections that are subjected to the rigors of both wave action and the "heave" of the hull in a seaway.
I just have not seen or heard of that. And it would surprise me greatly because all hulls, even so-called flat ones, are not really "flat," but have some curvature to them. But then again, my view here probably is more a function of my ignorance. :)

I'm going to post something on CSBB, as Bob Perry frequents that site, and I bet we can get a definitive answer on the issue. All joking aside, I most certainly could be very wrong. Let's find out.
 

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CD,

Thanks for our honesty.

Do you have any knowledge of how the new Beneteau 40 measures up? We are thinking about the new 40 not the new 43 as it would be out of our price range, but I am interested in what you may know of the new 40 design relative to the points you brought up.
No, sorry. Others may know that boat better. I have no first hand knowledge of that boat.

Brian
 

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I just have not seen or heard of that. And it would surprise me greatly becaue all hulls, even so-called flat ones, are not really "flat", but have some curvature to them. But then again, my view here probably is more a function of my ignorance. :)

I'm going to post something on CSBB, as Bob Perry frequents that site, and I bet we can get a definitive answer on the issue. All joking aside, I most certainly could be very wrong. Let's find out.

I used the term "flat" in a relative context. Next time you are strolling about a marina with lots of boats sitting on the hard, compare the fwd section hull forms and you will notice that some are less rounded- more flat, particularly toward the bow as some manufacturers use that shape form to gain interior volume.

The hull flex was most noticeable close to the design waterline. We were on a predominantly port tack pounding into a 4-6 ft sea with a stiff breeze for approximately 10 hours. Using a flashlight to cast a shadow across the hull interior, the flex was pronounced and observed by all of us, not just me. As it was close to the fwd bulkhead, I attribute the oil canning to the hull form and structure rather than lack of support evidenced by the proximity of the bulkhead.


Cruisingdad -
didn't notice a list but the boat was pretty packed, the stern definitely squatted which is an inherent trait of many contemporary hull forms, sole plates felt like walking on a see-saw, and of course a leak was evident directly over my berth... inevitable I guess.
 

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I used the term "flat" in a relative context. Next time you are strolling about a marina with lots of boats sitting on the hard, compare the fwd section hull forms and you will notice that some are less rounded- more flat, particularly toward the bow as some manufacturers use that shape form to gain interior volume.

The hull flex was most noticeable close to the design waterline. We were on a predominantly port tack pounding into a 4-6 ft sea with a stiff breeze for approximately 10 hours. Using a flashlight to cast a shadow across the hull interior, the flex was pronounced and observed by all of us, not just me. As it was close to the fwd bulkhead, I attribute the oil canning to the hull form and structure rather than lack of support evidenced by the proximity of the bulkhead.
This makes a little bit more sense to me. I bet you saw the flex a bit higher than at the design waterline. If you were in 4-6 foot seas beating into a stiff breeze, I bet you were heeling a fair amount, which means the topsides were well into the water and feeling the effects of the sea. I still find it odd that you would get oil canning very close to a bulkhead though, and I still have to question exactly what was going on, but you were there and I certainly was not.

In terms of your point about the flat hull form, it doesn't take much curvature at all to make the structure quite strong, or at least substantially more strong than if it were truly flat.

By the way, I don't think designers use flat underbodies to get more interior volume. They do that for performance and form stability. Indeed, flat bottoms actually decrease usable space below, as you have no bilges for storage, which means you need to get that storage elsewhere. Increasing beam forward gives you more volume, but I don't believe a deeper forefoot does that (though again, I could be wrong).
 

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I used the term "flat" in a relative context. Next time you are strolling about a marina with lots of boats sitting on the hard, compare the fwd section hull forms and you will notice that some are less rounded- more flat, particularly toward the bow as some manufacturers use that shape form to gain interior volume.

The hull flex was most noticeable close to the design waterline. We were on a predominantly port tack pounding into a 4-6 ft sea with a stiff breeze for approximately 10 hours. Using a flashlight to cast a shadow across the hull interior, the flex was pronounced and observed by all of us, not just me. As it was close to the fwd bulkhead, I attribute the oil canning to the hull form and structure rather than lack of support evidenced by the proximity of the bulkhead.


Cruisingdad -
didn't notice a list but the boat was pretty packed, the stern definitely squatted which is an inherent trait of many contemporary hull forms, sole plates felt like walking on a see-saw, and of course a leak was evident directly over my berth... inevitable I guess.

If I am not mistaken, the 400 has a very similar hull. SHe is untraditional of Catalinas, I suppose. THe 470 and 440 also have similar design. The 42 is rounded, more traditional.

You are right, K1. Walk the docks. Look at boats on the hard. There seems to be a distinct difference. You will find (my opinion) most "blue water boats" with a rounded hull. It is deep and curvatured. On the other end of the spectrum (what I feel is the newer design) is the flat bottom boats.

I will now jump into a very bad distinctio nbetween the two hull forms/shapes and some of their tradeoffs. I do this for the potential 423 buyer and others that have spent any time on both types.

Rounded Bottom​

Again, I find this typical of most "blue water" baots of early vintage especially. Dad's boat is a Tayana 42... a boat I have become quite knolwedgteable about for obvious reason. ANother boat of this type I have spent a lot of time around is a Valiant 42 (though the Valiant 42 is not as deep as the comparable Tayana... an interesting observation given its abilities). Another rounded bottom boat worth mentioning in the production class is the Catalina 38/380. We lived and cruised on our 380, so I know her well too.

I find that the rounded bottom boats, in general, have awesome, deep bilges. DO not discount a deep bilge and its obvious benefits. Other than considerable tank stowage, you will find that the deeper bilges allow for the inevitable water to make its way to the bilge while going to weather for long periods of time. They are also very good for lowering your weight aloft for long term sailing or cruising or just flat for performance. We kept all of our can goods (coated and bagged) in our bilge. We have also kept many, many other items, including many tools, bolt cutters, extra water cans/gallon jugs, etc. If it is something heavy and not something we will get too often, I try to find a way to get it in the bilge. Some things are not always good choices (like the tools mentioned above) without considerable caution as to keeping them dry. All boats leak... at least a little (Ooops, Bene and Catalina did not tell you that, did they!!).

ROund bottom boats handle differently then their flat bottom cousins. For one, they tend to roll more. This can be really frustrating at anchor and at sea. The heavier boats have the benefit of that roll becoming predictable. Once you get your sea legs, it is no deal. But inherently for those that are prone to becoming sea sick, I think it exhasperates the problem. Also, round bottom boats tend to be more tender. At a gust, they will lunge to leeward more than a flat bottom boat would. The difference is that the lunge, though quick, has a predictable stoping point. But it is still unerving the first many times. To be honest, I never got to where I was comfortable with teh roll on our 380. My wife especially did not like it. I found the Tayanas of the world, though still rolling and somewhwat apt to tenderness, were countered by their full/MF keel and sheer weight. The TV-42, for example, is about 38,000 lbs dry. That is a lot of inertia to get moving. A final aspect of note on the rounded bottom boats is their performance. I find them slower to weather and less prone to reach hull speed without a lot of wind behind them. However, I find them to be confortable and stable at all speeds. Even in a hard blow, dad's boat just clips along, predictably, though she gets to that "heeling" quicker then I like.

Flat Bottom Boats​

Almost all of the opposite is true, with some exceptions.

I find this the newer bottom design. It is typical on most performance oriented boats. Look at Giu's, or the first series Benes, or the Catalina 400 (pre-HN 307'ish). THese boats do not round over like other boats, but instead you will find them harder chimed (if that is the word on a sailboat). In most weather conditions, you will love this boat. She is responsive, very sure footed, and pretty fast. Hull speed is easily achieved (and in many cases exceeded). Her movement is slow and predicatble to weather. You may actually find your best point of sail is to weather, versus a beam reach. It certainly is not running, where I feel my boat is the worst performing.

My boat likes to sail flat (unlike Giu's... his is a much beter performing boat than mine). It takes a lot to get her rail wet and I am not sure we relly gain that much doing so. On my particular boat (as they changed the hull in the last couple of years), it is still deep enough for drainage to the bilge and points well. She also rides an anchor well.

The negatives, as you can guss, are many of the positives of the other boats. Although I was able to get my extra batteries in the "bilge" (below the foot boards), You simply cannot get a lot down there without eating up every bit of space. The diesel tank, though below the waterline, is actually higher than the batts. Same is true for the water tanks. I would much prefer if they could have put those thanks lower and made the bilge deeper - freeing up that space for 'living'. However, because of the many stringers and the way the hull liner runs 90% of the boat, it would have instead been a large congolomerate of many tanks making up one. In essense, it would have been expensive to do (something a production manufacturer is not apt to do). On the flip side, changing any or all systems on my boat is very easy and very accessible. Still, I would have preferred the opposite. I think Giu;s boat has the opposite... a huge plus.

So there are some things to consider as you now look at your boats. Look at the hull shapes and it will give you some insite into how she will sail in good and bad weather. It will also shed some light into her performace and liveability. And just think... all this you can get from simply looking at the outside (well, maybe).

Hope that helps you in your boat search. Take care,

Brian

PS Look at a Catalina 400 if the 40 is a boat of interest. She may be comparable - but she is traditional inside. Also, you may actually end up paying more than another boat of comparable size/length. The 400's have actually appreciated in value. Unheard of, huh?
 

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This makes a little bit more sense to me. I bet you saw the flex a bit higher than at the design waterline. If you were in 4-6 foot seas beating into a stiff breeze, I bet you were heeling a fair amount, which means the topsides were well into the water and feeling the effects of the sea. I still find it odd that you would get oil canning very close to a bulkhead though, and I still have to question exactly what was going on, but you were there and I certainly was not.

In terms of your point about the flat hull form, it doesn't take much curvature at all to make the structure quite strong, or at least substantially more strong than if it were truly flat.

By the way, I don't think designers use flat underbodies to get more interior volume. They do that for performance and form stability. Indeed, flat bottoms actually decrease usable space below, as you have no bilges for storage, which means you need to get that storage elsewhere. Increasing beam forward gives you more volume, but I don't believe a deeper forefoot does that (though again, I could be wrong).

I totally agree, especially about the latter. I wrote the thread under yours while you were posting this!! Great minds, Dan!!

Brian
 

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Discussion Starter #29
Thanks to everyone for the really informative posts. I had a retired surveyor friend read through these to help me sort them out. Here's his take on it all.

Regarding the hull slamming and oil canning: All boats slam to some extent when pounding to windward in waves, and whether one pounds worse than another is a very subjective matter. Can't really be measured. Of course, the larger boats won't jump around as much as the smaller ones (you know, mass and inertia and all of that), plus when you're getting spray in your face you build up a strong negative psycholgical feeling. Naval architects can usually evaluate the pounding propensity of one forebody shape over another, but almost all hull shapes are a compromise of sorts to meet the need for interior space and accomodations. High speed power boats have deep vee-bottoms to minimize the pounding, at the cost of added HP requirements. Even the America's Cup boats, long and skinny, have to accept some pounding and discomfort in trade for overall speed in differing conditions. Most boat builders are always experimenting with hull designs, but inevitably reduce the analysis to a "seat of the pants" determination. And rest assured that every manufacturer will claim that this new design is much better.

On oil canning, many owners mistake some deck flexibility for oil canning, when in reality they're describing a deck problem from delamination, sometimes calling it a trampoline in bad cases. Also, in a seaway, many lightly built boats will flex noticeably, and this, too, could be called oil canning by an untrained person. That kind of flexing almost always causes hairline crazing or cracks in the surfaces of gelcoat, particularly in the "sharp" corners or where the molded shape changes greatly. The term "oil canning" originated when motor oil was sold in quart cans where the top could be easily popped in and would pop out when you took your finger off. Sort of a pucker. And similar to what you'd see on a can of food that has gone bad, where the top has a slight dome that you can pucker.
 

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Thanks to everyone for the really informative posts. I had a retired surveyor friend read through these to help me sort them out. Here's his take on it all.



On oil canning, many owners mistake some deck flexibility for oil canning, when in reality they're describing a deck problem from delamination, sometimes calling it a trampoline in bad cases. Also, in a seaway, many lightly built boats will flex noticeably, and this, too, could be called oil canning by an untrained person. That kind of flexing almost always causes hairline crazing or cracks in the surfaces of gelcoat, particularly in the "sharp" corners or where the molded shape changes greatly. The term "oil canning" originated when motor oil was sold in quart cans where the top could be easily popped in and would pop out when you took your finger off. Sort of a pucker. And similar to what you'd see on a can of food that has gone bad, where the top has a slight dome that you can pucker.
Feel free to listen to some surveyor who wasn't there or from the consensus of a group of knowledgeable sailors who were and know the what "deck flexing" is - this has absolutely nothing to do with the issue here and most surveyors should be able to tell the difference...

Regarding the flat hull and pounding, I said both were relative terms - this boat has/does both compared to similar sized and priced competitors - again, your choice.
 

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Feel free to listen to some surveyor who wasn't there or from the consensus of a group of knowledgeable sailors who were and know the what "deck flexing" is - this has absolutely nothing to do with the issue here and most surveyors should be able to tell the difference...

Regarding the flat hull and pounding, I said both were relative terms - this boat has/does both compared to similar sized and priced competitors - again, your choice.

Yeah, Nika, I was going to follow-up and mention that while your surveyor's comments are interesting, they seem to focus on deck issues. K1 was specifically discussing oil-canning of the hull, not deck, in a moderately heavy but fairly typical seaway.

As for the pounding, my impression is that sailors in recent years have increasingly come to accept pounding as a fact of life with modern hull designs. Evidenced by use of words like "relatively moderate" when discussing the extant to which a tested hull pounds, as though this is a welcome attribute.

The flatter modern hulls have certain advantages over older designs, but their acknowledged propensity to pound is not one of them.
 

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Discussion Starter #32
Always a trade off it seems. I guess we shall have to live with it if we want light wind performance and the ease of sailing of these modern sailboats.

thanks
 

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Always a trade off it seems. I guess we shall have to live with it if we want light wind performance and the ease of sailing of these modern sailboats.

thanks
Nika,

If you're strictly planning to do coastal cruising/vacation sailing, where your exposure to pounding conditions can be limited by ducking in for cover, it is a very reasonable trade-off to make.

On the other hand, if you're talking about crossing oceans with your family, you should consider the effect on your long-term cruising plans of a 3-4 day beat to weather in a nasty seaway. It's challenging enough in a boat whose design minimizes pounding, but it can be punishing in a boat that has traded or compromised this design attribute for other advantages.
 

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Discussion Starter #34
I wholeheartedly agree. If we were going to do anything else other than coastal cruising I'd go for a heavier boat with a deeper keel, too. For what we have time to do, which is sail over to Bock or Newport and for weekend trips to Greenport I think we'll do fine with the Beneteaus.

thanks for your insight.
 

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I wholeheartedly agree. If we were going to do anything else other than coastal cruising I'd go for a heavier boat with a deeper keel, too. For what we have time to do, which is sail over to Bock or Newport and for weekend trips to Greenport I think we'll do fine with the Beneteaus.

thanks for your insight.
Absolutely. Great boat for how you plan to use it. I'd put it on my short-list too.

We have a member, tomaz_423, who owns one and he'd probably be a good resource if you haven't come across him yet.
 

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Don't worry with the pounding...maybe they pound a bit more than deeper narrower hull design, but it sure sails better...

It's a sailboat that sails...go for it, don't let it be an issue.

You can buy an Old Shoe that doesn't pound, but doesn't sail either..

And you will end up sailing more time, than pounding..

GO FOR IT
I don't know about that. My old wooden shoe will average 7.5 in 10 knots of breeze and run with a similar LOA plastic boat and when the wind is up over 30 knots, she'll run off and hide from them. We averaged 10 knots for a 100 NM trip in 40+ just fine. Granted, she won't run with Giulietta but neither will that 423.
 

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I don't know about that. My old wooden shoe will average 7.5 in 10 knots of breeze and run with a similar LOA plastic boat and when the wind is up over 30 knots, she'll run off and hide from them. We averaged 10 knots for a 100 NM trip in 40+ just fine. Granted, she won't run with Giulietta but neither will that 423.
Um, how big and what kind of boat is this? 7.5 knots in 10 knots of breeze? Is it a twin screw trawler?
 

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I've owned our 423 for 3 years now and sailed it up and down the Chesapeake Bay. At the mouth of the Potomac in about 30+ kts of wind we were seeing 4ft+ waves with a short period and the boat sailed beautifully, better than any other I've sailed. It is also an amazingly strong boat with stiffeners throughout and fiberglass that is solid. I can't imagine "oil canning", the effect of bending a plate and it "popping" back (with a loud sound) to its original shape when the load is released, ever occurring on this hull. It is a great boat and Beneteau did a great job designing it. Hearsay is not a design criteria, but if it can be proven I'd love the data be posted so all can know. Until then, it sounds like nonsense to this kid.
 

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I've owned our 423 for 3 years now and sailed it up and down the Chesapeake Bay. At the mouth of the Potomac in about 30+ kts of wind we were seeing 4ft+ waves with a short period and the boat sailed beautifully, better than any other I've sailed. It is also an amazingly strong boat with stiffeners throughout and fiberglass that is solid. I can't imagine "oil canning", the effect of bending a plate and it "popping" back (with a loud sound) to its original shape when the load is released, ever occurring on this hull. It is a great boat and Beneteau did a great job designing it. Hearsay is not a design criteria, but if it can be proven I'd love the data be posted so all can know. Until then, it sounds like nonsense to this kid.
Do you realize that this thread is just about 10 yrs old and the poster you are referring to who made the oil canning statement hasn't logged in for over 6 years...

Just saying this as you might not get the reply you are hoping for. :)
 

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Do you realize that this thread is just about 10 yrs old and the poster you are referring to who made the oil canning statement hasn't logged in for over 6 years...

Just saying this as you might not get the reply you are hoping for. :)
People still read these threads and buyers come across them when researching boats. Shorty seems to be one of the few posts on the thread answering the question instead of blah blah blah.

So a little slack
 
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