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Originally Posted by 302Sport
(Post 3649761)
Honestly if you have all winter to do it and your labor means nothing to you, pick up a set of arnesons like what's in the swap section for $7k, sell your other stuff and be way ahead of the game.
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I'd prefer the threes over bravos any day. As a quick guess, mount them with the prop shaft 3.5 to 4 inches below the hull.
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Originally Posted by dereknkathy
(Post 3652852)
x-dim on twins. is it to lowest point of keel? or bottom directly below drive. note, the swivel up-down where trim indicators go is center of crank-upper driveshaft for measuring purposes.
Originally Posted by kvogt
(Post 3652994)
I'd prefer the threes over bravos any day. As a quick guess, mount them with the prop shaft 3.5 to 4 inches below the hull.
For reference, my buddies 38 Cig flatdeck drives are 4" below, ssm IIIA, no boxes, no transom notch. Planes off just fine, no slip whatsover. My 38 Fountain, with transom notch, ssm iv, propshafts 1.5" below the bottom, is very prop sensitive. With the right props, it lays right over. With the wrong props, grab a snickers before you attempt to get on plane, cuz it'l be a while. |
Lol, the 3's are a lot different from a 3a aren't they? And yes my boat has a notch
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Originally Posted by lil red
(Post 3653007)
Lol, the 3's are a lot different from a 3a aren't they? And yes my boat has a notch
Internally they are different, gears and such. But externally from a dimension standpoint, they are the same. |
Oh ok, I thought the 3a had a lower like a 5
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IIIA's have the same size gearing as the V's do, also they are big shaft in the latest design, the first design still implimented a small shaft, and that was soon changed out... I just happen to have a set if you're interested... lol
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Sure my 3s and a case of beer? Lol
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Originally Posted by dereknkathy
(Post 3652852)
x-dim on twins. is it to lowest point of keel? or bottom directly below drive. note, the swivel up-down where trim indicators go is center of crank-upper driveshaft for measuring purposes.
Originally Posted by kvogt
(Post 3652994)
I'd prefer the threes over bravos any day. As a quick guess, mount them with the prop shaft 3.5 to 4 inches below the hull.
Just to clarify, x is not measured to the notch, but to the bottom. |
Originally Posted by A.O. Razor
(Post 3653273)
Directly below.
Why on earth whould you mount them so the prop sits lower than the current B1 setup? That will not take the full advantage of the drive, slow the boat down cosiderably and so on. You can get 3", 2", 1" and other spacers for the IIIs. They are surface drives and are supposed to be run as such, so are the cleaver props that go with it now a days. Don't forget that prop technology has come a long way since the IIIs came on the market. I would not go below 24.25 personally and then space from there, IF EVEN NEEDED! 5 blades, 6 blades, 20-21* rake ect. Lots of options available in terms of props. If you want to go fast. go high. Just to clarify, x is not measured to the notch, but to the bottom. KVOGT isn't talking from his a$$. He has a 107mph 38 Flatdeck with Arnesons that he built, his brother has a 38 Flatdeck with SSM V's and boxes, that he rigged from TRS, his good friend Tom had a 39 Chris Craft Stinger (same hull as the Excalibur Hawk) that had SSM IV's on boxes, which i believe ran into the 90's. Not too mention a 41 Apache they are re-rigging. I can tell you my buddies 38 Flatdeck Cig, with IIIA's mounted 4" below the bottom, while does plane well, has a slip of over 22%, with 4 blade 17" diameter props. Maybe some 10k dollar Herrings would help lower that, but 10k dollar props ain't in the budget. And not sure if they are in LIL Red's budget either. With 600-700HP per side, in that Excalibur Hawk, Mounting the drives even with the running surface is probably gonna = a poorly planing boat, ineffecient cruising, and the engines mounted very high. He'll need those blower scoops, even without a blower. My old excalibur hawk had TRS, and the drives were in the basement. Standard 3" flame arrestors barely cleared the stock hatch. If I remember correctly, the factory TRS propshafts on mine were like 7" below the bottom!! Running 4 blade hydromotive props on that setup I had about 15% prop slip. Going up in X dimension doesn't always mean going faster. My buddy Bob has a 2006 42 Fountain, stock 525's, and XR drives. Boat was never that great at planing off, even with 5 blade P5X props. Added 2" spacers, actually gained a couple mph, planed better, and cruised better. Same exact deal with my friend Mark's 38 Flatdeck cig with Konrad's. He ended up running spacers because the boat just ran better with them, and thats with 5 blades too. My overall opinion is install the III's, keep the propshafts about 3.5-4" below, run a basic 4 blade SSM prop that wont cost more than the drives themselves, nor will they tear them up like a 6 blade running at the surface (III's do have their HP limits). Enjoy a boat that will plane off with a full tank of fuel and a boat load of hot chicks. Also, enjoy a boat that won't blow the props out in heavy seas. Getting on plane with III's mounted at the running surface in 5ft swells will be real fun. I can tell you my 38 Straight bottom Fountain with the shafts 1.5" below, even with the right props, has a tough time getting on plane in heavy seas. However, when up and running, my prop slip is only 10%. Fountain factory rigged mine, but its a totally different animal than yours. Smaller, lighter, pad bottom, etc. If going fast is the ultimate goal, get a different hull. If you wanna bring the drives way up, sell the III"s, get a IV or V. That was a drive that was INTENDED to be a surface drive. Look at the SKEG on a III, then look at the Skeg on a IV or V. There was a reason the skeg is so large on the IV and V. The III wasnt introduced as a surface drive. The entire reason mercruiser introduced the SSM IV, was in answer to Howard Arneson's drives in the 80's, since the Arneson equipped boats were doing so well and beating the SSM III equipped boats. |
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