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Kiztope

2005 Sunesta 274 8.1 - dog slow.. What's wrong here?

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And for what it's worth, my old 254 Sunesta, with same deadrise, and running 300hp 350MAG, did 49.5mph via GPS, so things don't sound right here...

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8 hours ago, Hatem said:

 

8 hours ago, Hatem said:

Those are some pretty incredible numbers for a Signature 276, wow good for you.  Your F6's are probably what are pushing you up that high.  

Just to clarify, the F6's are on my Crownline 270 BR, which is almost 2K pounds lighter than my Sig 276.  The Sig 276 has F5's on it, I don't think it would turn max 4600 RPM with F6's on it.

 

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On ‎7‎/‎11‎/‎2019 at 8:52 AM, cyclops2 said:

Less deadrise is almost always the faster LOADED boat.

Steeper deadrise number is a slower boat. But a softer riding boat.

But that's not the common theory, though.  The greater the deadrise (meaning the sharper the V in the hull,) the faster the boat is and much more capable of cutting through waves so you can build a lot more speed. Although the lesser the deadrise, the more comfortable the ride is according to the info out there.

On ‎7‎/‎11‎/‎2019 at 12:23 PM, Toddavid said:

Yah, you confuzed it. Flatter hull (less deadrise) has less drag as is thus typically faster than equivalent vee with more deadrise.

Ok, thanks for the correction.  Kinda doesn't make sense when you think about it although the deadrise that really matters is more at the center of the hull towards the rear and transom as the boat is planning, the front V is mostly above water line.

Put another way, more deadrise generally equals the ability to run at faster speeds before pounding becomes excessive.

https://www.boatingmag.com/all-aboard-boats-whats-deal-deadrise/

That's what I meant where a boat with a 13 degree deadrise like the OP's 2005 Sunesta is not going to be as fast as say your new 2014 264 Sunesta with what, a 22 degree deadrise?  I believe that is measured at the transom.  But my point was that the lesser the V angle and deadrise, the less speed the OP should expect even with an big block 8.1.  Or am I still wrong?

 

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The go fast boats are running 24 deadrise, Baja, fountain. More stable in high seas and ability to cut the waves rather than slam them and usually have a stepped hull or hull pad to really keep them up out of the water at high speeds. Also waxing you boat to make them go faster is getting to be a myth also. Watch the race boats, they actually sand the hull to create an area to hold air against the hull rather than water. Think of it as pulling a 2x4 through the mud. The Chap SSI only uses a 21 degree rise on the bigger ones.

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We have engines so powerful a oil tanker can get on plane.  The extreme shapes available can make anything fast in any wave conditions.

The... wave piercing hulls... are great rough water hulls.  They are also fast in rough water...…….Interesting reading.  Next family boat ?

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My understating was the flatter the hull, the more it would ride on top of the water when it’s smooth, creating less drag. However when things got rougher with the water surface, the lack of vee results in a rougher, pounding ride.

The vee cuts through the water when rough, resulting in a smoother ride, but also cuts through when the water is smooth, creating more drag.

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7 hours ago, Toddavid said:

My understating was the flatter the hull, the more it would ride on top of the water when it’s smooth, creating less drag. However when things got rougher with the water surface, the lack of vee results in a rougher, pounding ride.

The vee cuts through the water when rough, resulting in a smoother ride, but also cuts through when the water is smooth, creating more drag.

Absolutely, as it's all about wetted surface. Flat bottom boats pound like crazy. A deep-V go fast will only go fast if you have enough speed to get a great percentage of the hull lifted out of the water. The racing Catamarans for off-shore are fastest as they lift and ride on a cushion of air. They did not dominate their class for many years as they were horrible in rough water, and had to slow down, and the true deep-vee's could use their hulls and although slower, could still maintain more speed in the slop than could the cats. The key for us mere mortals is finding a good compromise based on how we are going to use our ride. I like the Chap 256 for the Upper Chesapeake Bay as it has enough dead-rise to get you home dry if it turns sloppy, and I can achieve 3 mpg on a perfect day at 35 mph. Moving to Florida, my boat of choice is the Cobia 277CC with twin 250 Yamahas. Variable dead-rise hull, with steep attack at the bow, and rides flat and smooth in a chop up to 2'. Even at 3' + you can maintain decent speed but best economy is found at 27 mph and she will achieve a best of 2.6 mpg. Even at 500 HP the thing will barely hit 50, whereas the 256 With 425 HP will run north of 60. I do plan to do some off-shore fishing in Florida, and I'm willing to sacrifice speed and efficiency for ride quality. W

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13 hours ago, Mi3sons said:

The go fast boats are running 24 deadrise, Baja, fountain. More stable in high seas and ability to cut the waves rather than slam them and usually have a stepped hull or hull pad to really keep them up out of the water at high speeds. Also waxing you boat to make them go faster is getting to be a myth also. Watch the race boats, they actually sand the hull to create an area to hold air against the hull rather than water. Think of it as pulling a 2x4 through the mud. The Chap SSI only uses a 21 degree rise on the bigger ones.

That's pretty much my understanding as well.  I've spent hours at boat shows talking to sales guys about hull designs and deadrises and all that.  Every once in a while you actually get someone who sounds like they really know what they're talking about and especially with the Formula dealer.  Seems that is some of the best source of information as they seem to understand not only what they're selling, but the complete package from forming the mold all the way to he final fit and finish.

One thing I saw that you just reminded me of when you mentioned "stepped hulls" was this, here.  Can't remember what brand it was but I think is was either Grady White or Boston Whaler or maybe even a CC, but I doubt it.  Essentially it's a stepped hull (or even a cutout) at a 45* angle from the outer edge going forward towards the keel but the strangest part of it is that is was covered?!  Ever see anything like this?

mjbIlav.jpg

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