SC Hull Question?

hiliner222 · #1 02-03-2012, 08:36 PM

Looking at a 20 Sceptre and i looked at the specs on this great site and it said the 20 Sceptre has only a 16 degree deadrise at transom? The 23s say 20 degrees. My question is as they are variable degree deadrise is that the angle in the middle or are all three angles added up and 16 is the average of the three, or maybe it'a a straight line from the keel to the chine. I figured they had more deadrise than that with the word on how well they ride. Most boats i've seen with less than 22 don't ride so well to me. Anyone? Thanks.

Iv;e never riden in one, i'd hate to get this 20 and have it ride like crap. Maybe look for a 23 with 20 degree?

DonV · #2 02-03-2012, 09:37 PM

The VDH is from bow to stern, the sharpest angle is toward the bow, for entry into waves, the flatter "deadrise" is at the stern for better side to side stability. There are other factors like the way the chines are designed for re-entry back into the water....an air cusion effect. Lots to learn.

hiliner222 · #3 02-03-2012, 09:49 PM

OOOH I see, I thought there was a different angle between the keel and first strake, another angle beteen strakes and a third between upper strake and chine at the stern? Looking at some pics thats what it looked like. I better look again, huh? Those are reverse strakes correct? So they dont help much to lift on plane as a normal lift strake? Willing to learn and understand these great reputation boats, thanks.

hiliner222 · #4 02-04-2012, 01:32 AM

Quote:

Originally Posted by DonV

The VDH is from bow to stern, the sharpest angle is toward the bow, for entry into waves, the flatter "deadrise" is at the stern for better side to side stability. There are other factors like the way the chines are designed for re-entry back into the water....an air cusion effect. Lots to learn.

Don, Here is a Seacraft brochure that explains it for us.

hiliner222 · #5 02-04-2012, 01:36 AM

I knew what you meant as most boats have a variable as you go from bow to stern. What i'm talking about is at the transom, and sure enough there are three different angles as you move up from the keel to the chine. Great design after reading this brochure it makes sense now.

hiliner222 · #6 02-04-2012, 02:36 AM

I was just looking at the patten on here and the hull (at the transom) has 21 degree from keel to first strake, 13 to second strake, and 10 at top strake to chine. So this is a variable variable hull, wow. Horozontal and vertical,amazing.

Bushwacker · #7 02-04-2012, 06:36 PM

Quote:

Originally Posted by hiliner222

I was just looking at the patten on here and the hull (at the transom) has 21 degree from keel to first strake, 13 to second strake, and 10 at top strake to chine. So this is a variable variable hull, wow. Horozontal and vertical,amazing.

Congratulations on doing some through research hiliner! Those numbers quoted in Mr. Moesly's patent are for the very first SeaCraft, the Moesly 21 (http://moeslyseacraft.com/SC21Brochure.aspx). On the 20' hull, I believe the deadrise on the inner panel is closer to about 18 degrees, although the numbers for the center and outer panels are about the same. I believe Big Shrimpin previously posted the exact numbers for the 20' hull on here some time ago. The 16 degree deadrise number quoted in the brochures is the average at the transom, measured from center of keel to the chine. There is another unique feature on the 19 & 20' hulls . . . if you sight along the chine from the front, you'll notice that there is a slight wedge shape to the outer panel (it slopes down at the back), which I suspect helps the boat get on plane at low speeds. As mentioned in the patent, a deep-V hull lifts further out of the water as speed increases, and I believe that outer panel is almost completely out of the water by the time you get up to about 40-45 mph! That outer panel wedge may be there in all the other hulls too, but I've never looked for it.

I believe the aeration created by the vertical steps (Click on the link in my signature to see a good photo of this) is the key to the soft ride and low drag of all the SeaCraft hulls. When I showed that photo to Mr. Moesly, he said that back in the early 60's, they spent HOURS at Lake X with a 21 trying to get a shot like that! A good buddy of mine that's a great photographer managed to get that one and a few others off Key Largo with Skip driving Carla's Bowrider, which made a great camera boat!

The vertical steps are much taller on the 21 than any of the subsequent models. I've ridden in the 18, 19 Bowrider, 20, 21, and 23' hulls, and IMHO the Moesly 21 is the best riding one of the bunch. Not surprising, since Mr. Moesly raced it in very rough conditions in the offshore powerboat races in the 1960's, totally dominating the outboard class, even beating some of the bigger inboards with 5X the power! If you look at the front view of Island Trader's 21 that he posted recently with the windshield mock-up, I think you'll get a feel for why it rides so well in big seas!

Haven't ridden in the Seafari 25, but I'd think it's ride is probably very close to the 21, since the hull lines up front are very similar. Naval architect and CSC member Big Fluke has tested a Seafari 25 extensively in big seas off Hawaii for his company, and he said it's "the most seakindly small boat we've ever tested!" They all ride great for their size, however, so do yourself a favor and find a CSC member near you and go for a ride! You will not be disappointed! Denny

Blue_Heron · #8 02-04-2012, 08:42 PM

Quote:

Originally Posted by Bushwacker

Haven't ridden in the Seafari 25...

Well, we're just going to have to rectify that. Maybe I'll drag mine to the keys for lobster season this year. If that works out, I'll bring it by Skip n Carla's and we can go for a ride. Someone needs to get Nobones past that "pig" thing anyway.

Dave

cdavisdb · #9 02-04-2012, 10:12 PM

Can't compare the 21 and the 25, yet, but I can say the 25 Seafari is light years ahead of my last boat, a 24 Seabird, 24 degree deepV, same weight as the 25 and no slouch as as rough water boat. There is just no comparison. Maybe when Island Trader gets done and we get a rough day, we can have a shot out comparing the two hulls.

Bushwacker · #10 02-04-2012, 11:20 PM

Quote:

Originally Posted by Blue_Heron

Well, we're just going to have to rectify that. Maybe I'll drag mine to the keys for lobster season this year. If that works out, I'll bring it by Skip n Carla's and we can go for a ride. Someone needs to get Nobones past that "pig" thing anyway.

Dave

Sounds like a plan! That 25 Seafari is looking NICE! Can't wait to see it!