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Old 07-16-2009, 06:57 AM
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Default Flat Bottom vs V Bottom

Here's a topic that could go either way. I feel that a lot of people look down on flat bottoms because...well there flat. A lot of people seem to think that flat bottoms are only for inner bays but from my experience with them I know what they are capable of so.......
Flat bottom vs V bottom what's the pros and cons? Just want to see what the publics knowledge is like when it comes to Flat Bottoms.

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Old 07-16-2009, 07:05 AM
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I have never owned one and have seen the video of the guy who built one and went out in the atlantic with great results.

I do see some out in the bay and in 1-2 foot of chop is does not look like fun after a few minutes.

My thought is, yes they are great for shallow drafts and pole/sight fishing,,other than that its up to the owner and what they can handle,,,
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Old 07-16-2009, 07:06 AM
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carolina skiff's are amazingly popular here, but i've got no experience in them
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Old 07-16-2009, 07:47 AM
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I had a carolina skiff j16 with a johnson 25, about 15 years ago it was a fun boat but it beat the crap out of you in any chop. When you got off the water in choppy conditions, I swear as you were walking to get the truck you would actually be still bouncing. We probaly could of slowed down to help but that never really entered the brain back than. Caught alot of fish out of it thou.
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Old 07-16-2009, 07:53 AM
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I have a 19' Carolina skiff and have been pretty impressed with its abilities considering its weight and shape. It handles swells well (floats over them) and is very stable when at rest. It also has a shallow draft and is fuel efficient. It is also really light and easy to trailer and launch. I use it in bays, inlets, lakes and rivers and it does well in all. I don't fish far beyond the inlet though even in decent weather. I have had it 5 miles into the ocean off NJ in 3-4' swells and it was fine but made me nervous.


As far as negatives, it is rough-riding in chop. If you try to go fast in a chop you will really pound. It is also really wet in chop. Sometimes on windy days I get soaked, even at low speeds. And when I say soaked I really mean it - as if I went swimming. I have never owned a V-bottom boat but I have been in them. They obviously will keep you drier in chop. The Vs will weigh more and take a lot mor fuel to power. The issue of draft I think is overrated in most situations since the difference is only a few inches - the main time the fltat bottom is an advantage for draft is when you are poling since with the engine down neither flat or V-hulls will run in under 2' of water without a jet.

I would say a flat bottom definately has it's place but for larger waters and windy conditions I'd rather have a Vee hull or some type of modified V.

Most of the benefits I have described have more to do with comfort than safety. I have heard that the flat bottoms are relatively safe in that they don't readily capsize (I don't really know this for sure). I am curious though about which design would be safer (as opposed to more comfortable) in similar sized boats. Anyone know anthing about which is more or less likely to capsize in extreme conditions?

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Old 07-16-2009, 08:05 AM
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I have a 16 mckee not flat but close and it will beat you to death in any chop. Flat bottems are good for shallows and tend to have a lot of room but ar'nt known for their smooth ride.
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Old 07-16-2009, 08:10 AM
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i would think that flat bottom boats woud be more fuel efficient but when it comes to common sense I just think that there ride would suck because of all the surface area
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Old 07-16-2009, 08:15 AM
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Combine the attributes of both with a warped-plane hull ...

Sharp entry to get through the rougher water and shed the water away from the boat. Yet a flatter transom deadrise for fuel efficiency, stability, shallow draft, slower speed planing, etc. Combine the tapered deadrise with an appropriate length to beam ratio and you have a great boat for big and shallow water. This style hull allows for moderate speeds in rougher water and still holds many of the attributes of flatter bottom boat. Key to a decent ride with this hull is to keep the bow down in a head sea and keep as much of the hull length in the water without "launching" the hull.


Entry




Hull shap from the side



Transom deadrise



BTW, this 27' boat can reach ~40mph at wot and obtain over 3mpg at cruise with just a single 225 outboard. A deep v would probably require near twice the hp and get half the fuel mileage at teh same length.
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Old 07-16-2009, 08:48 AM
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Having owned several flat bottom Carolina Skiffs, I'd have to say they do have some advantages other than shallow draft to make up for the kidney-busting ride in a chop.

A flat bottom hull needs very modest power compared to a V-hull, mostly because they get up on plane so easily. My 24 Carolina Skiff does just fine with only 90 hp, a v-hull might need twice that much. Even running a 5000 rpm cruise, I'm getting 5 NMPG.

Flat bottoms can also hold plane at very low speeds, as low as 10-12 knots. This is a big help when you do run into some chop. I trim down and slow down, and can ride suprisingly well in some fairly rough stuff.
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Old 07-16-2009, 09:18 AM
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We build a 16' Flat bottom and equipped with a 40Hp E-Tec it can reach speeds upwards of 38mph while still having excellent fuel economy. Our 20' Model with a 75Hp E-Tec runs 43mph while maintaining good fuel economy. Our 18' V bottom runs about 52mph with a 150Hp E-Tec...and likes the gas. I started this forum to see how people feel about flat bottom boats...I myself love them and this is coming from someone that runs both Flat bottoms and V bottoms.

You could say that our boats are a little different then the average boat...www.admiraldrive.com
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Old 07-16-2009, 10:25 AM
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I have a Polar Flats 1788 and it does beat you up a little in choppy seas. I Mainly stay inside the harbor but have been known to go outside at times. The biggest advantage I can see with a Vee hull vs. a flat is a Vee would cut through waves whereas a flats rolls over them. Big difference cutting through as your bow probably won't go as high which I would think reduces getting wet. My flats rolls up and over and can come down pretty hard at times. The hull is stepped so the design somewhat reduces the wet factor (sends waves out, away from the hull) but on a windy day, you will get a pretty good spray. That being said. it has a draft of about 8 - 10" so I can really creep up into some skinny water. It has a 2-stroke 70 hp Yamaha and can get up to around 38 with 4 people and gear (according to Garmin). That is fast enough with wife and kids (too fast for wife).
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Old 07-16-2009, 11:57 AM
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Nice post B-Faithful, well said and I agree with you completely. It's interesting in that I build a very similar boat in sizes from 24 to 40 and recently built a mold and one boat from the mold at 26' 10 1/2", powered it with a 200 hp Suzuki and got 43 out of it.
I think the OP was referring to a flatter boat then that and although I don't have a lot of time to elaborate, I will agree with him that the merits of some flat bottomed boats are generally misunderstood.
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Old 07-16-2009, 12:23 PM
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I like flat bottom boats. Tough to beat the efficiency in calm conditions, but I do agree with other posters that they don't tend to handle as well in rough choppy water. Certainly good for bays, rivers, lakes, and other calmer water. While they may be able to handle more, they are not going to be as comfortable as a deep vee in rough stuff but may be more comfortable when the weather isn't so bad.


bryans, much better post btw
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Old 07-16-2009, 01:42 PM
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C-Dory is a great example of a relatively flat bottom hull that's very seaworthy. It will pound in chop but requires less HP and less fuel and will not rock like crazy while drifting.

I own the Cat version but I have trialed the monohulls in chop.
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Old 07-16-2009, 01:43 PM
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Quote:
Originally Posted by B-Faithful View Post

BTW, this 27' boat can reach ~40mph at wot and obtain over 3mpg at cruise with just a single 225 outboard. A deep v would probably require near twice the hp and get half the fuel mileage at teh same length.
Having started out in a '81 Whaler Montauk I know how bad a flat bottom hull can pound in any sized chop. I still think its a great boat but it has its place and its use is limited by weather conditions.

If you are looking to venture offshore in a monohull nothing beats the ride of a Deep V.

B-Faithful for comparison sakes my current boat is a Contender 25. My boat has a deadrise of 24.5 degrees, has an LOA of 28', drafts 19''. Its powered by a single Yamaha OX66 250 tops out at 43 mph and cruises at 30 mph. So basically a deep v does not require twice the HP of your boat. I'm not sure what mpg I get but a reasonable guess would be around 2 mpg at cruise. I'm sure if I had a four stroke my mpg number would be pretty close to yours.
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Old 07-16-2009, 03:25 PM
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Quote:
Originally Posted by squirm88 View Post
Having started out in a '81 Whaler Montauk I know how bad a flat bottom hull can pound in any sized chop. I still think its a great boat but it has its place and its use is limited by weather conditions.

.
You can't consider a 81 Whaler Montauk to be a flat bottomed boat and definitely a case where some V. is not better than none.
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Old 07-16-2009, 04:50 PM
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Quote:
Originally Posted by commuter boats View Post
You can't consider a 81 Whaler Montauk to be a flat bottomed boat and definitely a case where some V. is not better than none.
No question the hull is not as flat as say a Carolina J16, it was flat enough that I had to come off a plane to cross a boats wake in order to avoid losing a kidney. I can imagine it would be even worse in a J16.

I'm not saying its a bad boat or that I ever felt unsafe on the boat. I'm just saying the boat was best used in protected areas. I have no question a flat bottom hull is efficient, stable and can get into some skinny water. However if you plan to use a boat for offshore fishing then a true deep v or a cat would excel.
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Old 07-17-2009, 07:43 AM
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A narrow hull will also ride softer in the waves and will be more efficient. Case in point, I've run a 26-foot flat-bottom with 60-inch bottom width at 40mph with a 115hp four-stroke Merc. What is interesting is that this boat also has a pocket tunnel, which generally costs you about 4-5mph on the top end. It is a heavy boat and rides well in the chop, gets a little wet in 2-footers, and 3-footers is about the max I've had it in - pounds some in the 3's and will soak you, but will get you home just fine.
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Old 07-17-2009, 01:58 PM
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good performance squirm... I doubt many deep v's are getting numbers like yours.

Long boat, I agree with the length to beam ratio as well. It certainly is one of those factors that affect ride.
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Old 07-17-2009, 02:34 PM
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Quote:
Originally Posted by squirm88 View Post
Having started out in a '81 Whaler Montauk I know how bad a flat bottom hull can pound in any sized chop. I still think its a great boat but it has its place and its use is limited by weather conditions.

If you are looking to venture offshore in a monohull nothing beats the ride of a Deep V.

B-Faithful for comparison sakes my current boat is a Contender 25. My boat has a deadrise of 24.5 degrees, has an LOA of 28', drafts 19''. Its powered by a single Yamaha OX66 250 tops out at 43 mph and cruises at 30 mph. So basically a deep v does not require twice the HP of your boat. I'm not sure what mpg I get but a reasonable guess would be around 2 mpg at cruise. I'm sure if I had a four stroke my mpg number would be pretty close to yours.
I think B-faithful is correct. The more boat you have in the water the less speed and mpg will result. You will out perform him in the rough stuff and he will out perform you on the drift, fuel economy and price.

I like 4 strokes but i think in your case you would get better fuel mileage, hole shot and speed on a high Hp 2 stroke.


Very impressive for that big boat to do 43 wot with a single 250.
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