Redwing 21 To "V or not to V"

[hoss]

I seriously thinking of building the Redwing 21 http://cmdboats.com/rw21pilothouse.htm?cart_id=b0b620f2d89878267354c47 37ab5cc78. I'm going to be using it on the lower Great Lakes, and in protected water. The information states there is a "V" hull version available. I emailed Karl Stambauch (the designer) about it and I got the impression he liked the flat bottom hull better. What do people think? To "V or not to V" for the above use. Thanks Ted

[bainbridgeisland]

I believe there is one significant advantage to a v-bottom that most folks don't realize. Underway, a v-bottom motorboat generally has better stability than a flat bottom boat. Here is why.

The stability of a v-bottom boat when underway is from the relative location of the center of buoyancy in relation to the water plane as well as significant dynamic stability due to the water flowing across the v. If the boat tries to heel, the angle of the bottom to the flowing water changes, forcing the depressed side to pick up more dynamic lift and the lifted side to loose dynamic lift. This phenomena becomes pretty noticeable when a 20' boat gets to about 5-knots and it is the dominant stability force at about 9-knots and above (though this depends on deadrise angle).

The stability of a flat bottom boat when underway is mostly from the location of the center of gravity in relation to the waterplane. There is some added dynamic stability but it is only a small percentage of the potential of the v-bottom boat.

If you plan to power your boat to travel around 5-knots or less, the flat bottom has advantages of initial stability (i.e. at rest), shallow draft and ease of construction. However if you plan to go faster, you will probably have better stability when underway with the v-bottom configuration.

David Mancebo

[hoss]

Thanks David. Anyone have any thoughts
-on suitability on the Great Lakes
- would a V hull be more or less fuel efficient

Thanks Ted

[Mark Van]

I'd go with the V-bottom, flat bottom boats are no fun heading into any kind of a chop. Flat bottommed boats are slightly easier and quicker to build, but I don't think the time saved is worth it. (speeking from the experience of living on a flat bottomed boat for 4 years.)

I don't think there would be any difference in efficiency. A V bottomed boat may also be easier to line up on the trailer.

[Zimmer]

I do not think you would see a bit of difference in fuel efficiancy. A v bottom will however be infinitely more difficult for you to build.

The lakes have some hefty weather at times and any time of the year. Go with the v bottom. You will not be sorry you did. Flat bottom boats are for people who cant figure out how to build a boat bottom that has deadrise.

[bainbridgeisland]

Originally posted by Zimmer:
A v bottom will however be infinitely more difficult for you to build.I don't think so. V-bottom, plywood boats are only hard to build when they are poorly designed. Some V-bottom boats (constant deadrise for example) are easier to build than some of the flat bottom boats out there.

An important thing to remember is that hull construction is not even 1/2 of the total project. For most boats it is 20%-30%. So even if you were to spend a little more time on the hull to get just what you want, it is small potatoes.

[Ron Williamson]

Regarding suitablity for the Great Lakes,like so many other things,it depends.
My opinion is coloured by living on a lee shore.
Puddling around on a nice day,not too far from land,sure.Otherwise,that boat is too slow to outrun bad weather and too small to stay out in it.
R

[Zimmer]

Some V-bottom boats (constant deadrise for example) are easier to build than some of the flat bottom boats out there Which ones? I would really like to hear just what v bottom is easier than a flat bottom.

[Zimmer]

Still waiting.
:rolleyes:

[ 11-28-2005, 12:08 PM: Message edited by: Zimmer ]

[JimD]

In my personal experience the only thing I know of that's at all hard about building a sheet plywood hull is if the design calls for the plywood to make bends beyond the plywood's flexibility. The most likely place for this to happen is at the bow of a v bottom. But it isn't always a problem. In fact it rarely is. It depends on the designer's experience with the limitation of plywood's bending ability and a careful look at the design should give the builder a pretty good idea of what to expect.

Aside from that it bugs me that the proponents of the flat bottom always want to use ease of construction as a selling point which IMHO is the poorest reason to choose a flat bottom. I wonder how many first time builders have gone for a flat bottom because someone told them it was hard to build a v bottom and they ended up spending all that time and money building the wrong boat? Sure, it may be easier to build a flat bottom and it's ok to say so but not to the point of implying that it is somehow very difficult to build a v bottom. It isn't. The reason to build a flat bottom design is because for whatever reason the builder feels a flat bottom will be better for the intended use. Construction degree of difficulty between flat and vee is so similar in most cases it barely is worth a mention.

[hoss]

The ease of buiding means little to me, I just want to do it right the first time. When it comes to building, some flat bottoms are difficult to get fair any flat spots or hollows really show up. where as in a V hull they are more hidden. Also a flat bottom has to be thicker to hold the same load. I am a little concerned with comments on the boat on the Great Lakes. It seems to me that any boat can get into trouble on the lakes (even freighters) in really poor weather. How big would I have to go to feel safe?

[Chris Stewart]

Originally posted by hoss:
How big would I have to go to feel safe?The Titanic was 882.75'.

[JimD]

hoss, check out other design websites and I think you will see that almost all the ones similar in size and usage that you have in mind are vee bottom. The few flat bottom designs I've seen tend to be long and narrow, or have dory/sharpie attributes, which seems to me are mostly attempts to overcome the inherent problems of flat bottoms.

[ 11-28-2005, 04:18 PM: Message edited by: JimD ]

[hoss]

Good point about the Titanic. I have been looking for a design for over 6 months and I keep coming back to the Redwing 21 (although the V hull version is looking a lot better). I am very open to any other ideas on which plan would be better. Thanks Ted

[Tom Lathrop]

Originally posted by Zimmer:
A v bottom will however be infinitely more difficult for you to build.
Using ther same standard of accuracy, a V bottom is infinitely better than a flat bottom.

Both statements are rubbish.

To gain the same rigidity as a V, a flat bottom would need to be considerably heavier, especially if the V is given a sole and floors.

I'm sure Mark Van Abema can expand quite a bit on the virtues of different hull bottoms. His first live aboard cruiser was a round bottom and the second is a flat bottom. Ask him what his next would be.

I am lodged in the V bottom camp for lots of reasons which have been enumerated many times by many people. I also think that those in the flat bottom camp will probably remain there, regardless. :rolleyes:

[hoss]

Tom has anyone built your 20 footer yet? I really like your boats but I am still stuck on the displacement hull/economy idea. I think I am slowly (pun intended) being talked out of it however!

[JimD]

Sam Devlin's 22' Surf Scooter? Calls for a considerably bigger power plant though:
http://www.devlinboat.com/dcsurfscoter.htm

Or this by bateau:
http://www.bateau.com/studyplans/DE23_study.htm

[ 11-28-2005, 07:39 PM: Message edited by: JimD ]

[Tom Lathrop]

Hoss,

I have not pushed the 20 footer at all so no one knows about it. Was hoping one of the two that are out there would build and tell me how it performs. Chris over in Newmarket has one that he intended for Lake Muskoka. Is that close to you?

One answer to Zimmer's question about a flat bottom that would be harder to build than a V would a large boat. Stabilizing a very large flat bottom would require a lot of interior framing, bulkheading, thickness of the bottom or all three. Being three dimensional and of triangular shapes, a V is much easier to make rigid and can be stronger, lighter and less expensive in large sizes.

[ 11-28-2005, 11:22 PM: Message edited by: Tom Lathrop ]

[bainbridgeisland]

Originally posted by Zimmer:
</font><blockquote>quote:</font><hr />Some V-bottom boats (constant deadrise for example) are easier to build than some of the flat bottom boats out there Which ones? I would really like to hear just what v bottom is easier than a flat bottom.</font>[/QUOTE]O.K. been away for a while but I will bite though Tom covered some of the basics.

A flat bottom boat is easy to build compared to a V bottom boat when framing is easier, fewer joints are needed for framing and scantlings are the same. So, how can a v bottom be competitive or even faster to build? It can when these things do not apply, for example:

1. When the bottom scantlings of a flat bottom boat must be increased due to higher loading, a v bottom may not. This saves material, and can save labor (only need one layer for example). Also, the wide panels of a flat bottom boat often need more stiffeners (i.e. they often need more than a v bottom boat does).

2. When the bottom of a flat bottom boat is too wide for a sheet of plywood, a joint is needed. If making a joint already, the boat could be flat or v bottom without adding labor to the plywood portion of the job.

3. The extra joint needed when framing a v bottom boat compared to a flat bottom boat does not apply when the frames are cut from plywood. Thus, such a boat would have no additional labor due to framing. Also, one more joint on a frame is not terribly time consuming or difficult.

4. The bevel on the keelson and chine may be more complex on a v bottom boat. But it doesn't need to be more complex by very much. For example, you could build a constant deadrise hull where the chine bevel and keelson bevel are almost unchanging. Such a boat would take little time to true up the chine and keelson with a plane after cutting the bevel on the table saw. Remember, most flat bottom boats have beveled chines anyway and they mut be trued up before planking.

V bottom boats can of coarse be hard to build if poorly designed. For example: When surfaces are not developable; When extensive framing is required; When changing bevels cause the plywood joints to change from lap joints to butt joints; When longitudinal stiffeners must be steamed or laminated to take the designed twist; When inadequate stem structure make the chine’s hard to attach.... and so on.

There are a few v bottom boats out there that match most of these ideas. My point wasn't to get bogged down with flat versus v bottoms but to say the difference in difficulty need not be very much.

[Ron Williamson]

hoss
Back to safety,it depends on your intentions.

We know that you don't want to run from Sarnia directly to Tobermory in the middle of the night,in April(or November).
If you want to fish for the afternoon,near shore on a nice day in April,that's different.

Our boat is 32' and not near big enough or fast enough,when it gets ugly.Though,so far it seems safe enough.
R

[ 11-29-2005, 06:22 AM: Message edited by: Ron Williamson ]

[Zimmer]

I dont have time to refute your other 3 but will get back to them, this one however screams boguscity to me


4. The bevel on the keelson and chine may be more complex on a v bottom boat. But it doesn't need to be more complex by very much. For example, you could build a constant deadrise hull where the chine bevel and keelson bevel are almost unchanging. Such a boat would take little time to true up the chine and keelson with a plane after cutting the bevel on the table saw. Remember, most flat bottom boats have beveled chines anyway and they mut be trued up before planking.
That does not explain how a v bottom is easier to build than a flat bottom - it explains how some v bottoms are easier to build than others.

I will get back to you on the rest.

[mmd]

Zimmer, it appears that you are not too easily swayed by the opinion of others on topics of boat construction, and that is not necessarily a bad thing. For what it is worth, I'll throw my hat in on Dave's side of the debate. In vessels larger than rowboats, a well-designed vee-bottom boat is only nominally more difficult to build by an experienced builder than a flat-bottom boat.

There does seem to be a bit of an apparent credibiity gap between yourself and Dave on this subject, though. You, of no proper name, of no fixed address, and with no attributed boat-related experience nor professional credentials are refuting the experienced opinion of a professional designer who - like me - actively works with these types of problems a dozen or more times per year. At face value, this seems to be a losing proposition. Of course, you may well be a grizzled veteran of hundreds of boats and have the records and scars to prove it, but we'll never know if you hide that provenance from us.

A third possibility could be that you are who I think you are, and that you are restricted in posting under your real name. If so, I urge you to make your case clearly and without rancour, and we will all come away from the debate much the wiser.

[uncas]

mmd... :D
The bilge is trying to ignore him...and hence..he has moved north...For that, on behalf of the bilge..I apoloze for sending him your way...
You all up here are too nice!!!!
ps...I have seen all of your explanations etc...and you all have gone overboard to oblige him...
Really don't bother...

[ 11-29-2005, 08:34 AM: Message edited by: uncas ]

[Mark Van]

Tom mentioned my last boat being round bottommed, and my current boat being flat bottomed, but he didn't mention the 20 footer that I designed for my dad, which is V-bottomed. It is 1/3rd the weight of my boat, and half the length, but I would take it out in worse conditions than I would take my flat-bottomed boat out in.

Jus look at a V-bottomed boat as a flat bottomed boat with one more chine. Not too much harder to build. (I don't like the term "harder to build". before I built my first boat, I asked my dad if it was hard to build a boat, he said "No, it just takes a long time".)

[paladin]

re Chris' post above....you might recall the Titanic wuz built by perfessionals....but the Ark wuz built by amchoors....

[Tom Lathrop]

Originally posted by Mark Van:
Tom mentioned my last boat being round bottommed, and my current boat being flat bottomed, but he didn't mention the 20 footer that I designed for my dad, which is V-bottomed. It is 1/3rd the weight of my boat, and half the length, but I would take it out in worse conditions than I would take my flat-bottomed boat out in.

Jus look at a V-bottomed boat as a flat bottomed boat with one more chine. Not too much harder to build. (I don't like the term "harder to build". before I built my first boat, I asked my dad if it was hard to build a boat, he said "No, it just takes a long time".)I intentionally left it for you to comment Mark. Your experience and opinion of all three types mirror mine. Each has its zone where it might be preferred but I think the V is best all round.

[Mark Van]

Originally posted by Zimmer:
I do not think you would see a bit of difference in fuel efficiancy. A v bottom will however be infinitely more difficult for you to build.
I don't see how anybody can take someone seriously who makes a statement like that. Perhaps he doesn't know what "infinitely" means. A space shuttle isn't "infinitely" more difficult to build than a flat bottomed boat. It is supstantialy more difficult, but not "infinitely" more, since it is actually possible to build one.

[Zimmer]

I do not think you have it in you to build a space shuttle van. smile.gif

[Joe ( Cold Spring on Hudson )]

ZIMMER = TROLL

DO NOT FEED THE TROLL

[la.pirogue]

Down here we build flatbottom boats for rivers and bayous with shallow and calm water in mind.we build v bottoms for lakes and bays with deeper and sometimes rougher water. skill is optional.

[Mark Van]

Originally posted by Zimmer:
I do not think you have it in you to build a space shuttle van. smile.gif I didn't say that I had the skills to build a space shuttle, but it is obviously humanly possible to build, therefor not "infinitely" more difficult. Look up "Infinity" in the dictionary, you obvously don't know what it means.

[Zimmer]

Im a poet van so I took liscense. So sorry to offend thee sire.

redface.gif redface.gif redface.gif

[Robert W. Long]

I am relatively inexperienced, 2 kayaks, and part of a caledonia yawl. I am planning to build myself a 20 ft. simmons sea skiff, and am confused by this discussion. I read that the simmons is pretty seaworthy. I would be using it out of ft. bragg, ca. My stupid question is "Is it a flat or v bottom?". Also I would welcome opinions on the suitability of this boat for fishing of north ca, coast. Thanks. Robert

[wyndham]

If you've ever had to take a decent chop right on the nose in a flat bottomed boat you will appreciate the minimal additional effort required to build the vee bottomed version. It's not that much harder and the skill you gain will serve you well for the next botat.
And just so you know, if the first one comes out right you will build another, and another, and another.............

[Tom Lathrop]

Originally posted by Robert W. Long:
I am planning to build myself a 20 ft. simmons sea skiff, and am confused by this discussion. I read that the simmons is pretty seaworthy. I would be using it out of ft. bragg, ca. My stupid question is "Is it a flat or v bottom?". Also I would welcome opinions on the suitability of this boat for fishing of north ca, coast. Thanks. RobertThe Simmons is a V with low angle deadrise, not flat but certainly not a deep V either. A lot like a dory but with a wider bottom than most. It works well in coastal NC and near ocean water. Would probably be fine for you. It is similar to the Tolman Skiff used a lot in coastal Alaska.

[Bruce Hooke]

Originally posted by hoss:
I emailed Karl Stambauch (the designer) about it and I got the impression he liked the flat bottom hull better.I'd get back to Karl and say something like "it sounded to me from your last email like you prefer the flat bottom version; is that correct and if so can you tell me why?"

It is all to easy to misunderstand someone, especially when we are just talking about impressions, and, on the other side of the coin, there may be some good reasons why, with this particular design, the flat bottom version is a better way to go.

[Chris Stewart]

Originally posted by Bruce Hooke:
I'd get back to Karl and say something like "it sounded to me from your last email like you prefer the flat bottom version; is that correct and if so can you tell me why?"

And be sure to mention that you are planning to use it on the Great Lakes.

Chris Stewart

[Rick Clark]

Originally posted by Robert W. Long:
I am planning to build myself a 20 ft. simmons sea skiff, and am confused by this discussion. I read that the simmons is pretty seaworthy. I would be using it out of ft. bragg, ca. My stupid question is "Is it a flat or v bottom?". Also I would welcome opinions on the suitability of this boat for fishing of north ca, coast. Thanks. Robert V bottom better ride ...> flat pounds the water harder. V bottom when at rest rock& roll!!
Flat bottom and considering the wider the bottom the more stable at rest.
smile.gif
PS: the only stupid question is the question never ask, so ask away!!!!!!!!!!

[ 12-09-2005, 04:12 PM: Message edited by: Rick Clark ]

[L.W. Baxter]

I'll go out on a limb and suggest that maybe Mr. Stambaugh prefers the flat-bottom version because that is how it was designed. He started out with the idea of a flat bottom boat of a certain type to meet certain purposes and a certain aesthetic. He probably did the v-bottom version because he got requests for it, but may be a little disappointed by people who don't appreciate it for what it is. With a vee-bottom, it is simply a different boat, not the one he had in his mind's eye.

I've never designed a boat, but that is how I would feel about it if I had.

[ 12-09-2005, 10:43 PM: Message edited by: L.W. Baxter ]

[pipefitter]

In my experience,again I will say,If it rides on the surface it is going to give you what the water condition is.Flat or mild Vee isnt going to be a noticeable difference unless you could walk out of one into the other type at that moment. They will both be somewhat unpleasant to be in if you dont trim the boats to match the conditions.If you build it yourself you are going to love it regardless.Just dont go out when it is going to be rough in either case and if you do then you just learn to live with it.It's all good and better,even if only slightly better.
Alot of times you may have to change the build of a boat to match your avg conditions. If you are in mostly choppy water then you may have to situate where you are going to be driving from. Console more forward or more aft.The sweet spot so to speak in the way you are going to be driving the boat mostly.
I would rather be in a narrow flat bottom boat than a wide vee hull that draws the same water.

After that considered,the only other factor is wet or dry and you can dress for wet. Build what you like. It is still going to be better than what you can buy comparitively.

[Christopher Locke]

I'm going to take a chance here and weigh in with my $0.02, which is about what it is worth. I'm a complete novice but when I was looking for designs for my boat, a Green Island 18, one thing that I noticed was that building a V bottom boat pretty much requires that you build a jig in the "standard" way. While you can also build a jig for a flat bottom boat, some designers allow you to do without one. For any experienced boatbuilder, that probably doesn't make any difference, but it did (together with not needing to install or bevel a keel) make it look less intimidating to me as a first time builder, and that is one of the reasons why I went with a flat bottomed. I would like, at somepoint down the road, to build a boat in the standard way on a jig and expect that it will be V bottomed.

Having said all that, I don't know if Karl's design for the Redwing flat bottom is on a jig or not. If it is, then having to bevel the keel seems like the only major difference in construction to me.

Chris

[JimD]

[flat bottoms] look less intimidating to me as a first time builder And therein lies the problem. Flat bottoms look easier but as soon as you roll up your sleeves and start building you find out that its not the case.

[bainbridgeisland]

Christopher, though it sometimes looks intimidating, building a 'jig' is not usually hard or time consuming. Often the benefits make using a 'jig' worthwhile.

How long does it take to build a 'jig'? Here are a few examples:

34' cold molded ocean racer, 2 experienced builders, base structure, transverse molds, stringers, stem receiver, transom mount: 42 hours

16' hard-chine plywood motorboat, 1 experienced builder, base structure, transverse molds, stem receiver, transom mount: 6 hours

26' strip plank Monomoy surfboat, 2 experienced builders & 1 helper, base structure, transverse molds, 2-stem receivers: 31 hours

19' hard chine plywood sailboat, 1 experienced builder, base structure, transverse molds, stem receiver, transom mount: 5 hours

As you can see, the 'jig' for even a complex boat is not particularly time consuming to fabricate. For a simple boat, a 'jig' hardly takes any time at all.

But why take this time? Boats built without any fixturing are severely limited in shape. Thus performance is usually traded off for ease of construction. Most folks consider a day or two extra construction time a small price for improved performance over the life of the boat.

Another reason for using fixtures is that it can speed up construction. This is because a boat under construction is usually very flimsy (i.e. not rigid). This makes it hard to work on until enough structure is added to stiffen it up.

Why use construction methods without a 'jig'? For a narrow class of boats, construction is certainly faster. The problem is that today folks want to use the method on everything. Unfortunately, the method only saves time when used within that narrow class.

[Mark Van]

Building any boat over about 12 feet should be done on some kind of jig. Without a jig, you will be dealing with pannels as long as the hull, which can be difficult to move around. Also, it is much more tricky to get a jigless boat set up all square.