20' SeaCraft heavy motor

[DonV]

Originally Posted by gofastsandman

I used to see a gal and her young squids in a 4 cyl version. For a bit.
And then they would pull away into the sun.

I guess I need to get me some Lencos.

I think you meant to say Bennett's.

[gofastsandman]

Originally Posted by DonV

I think you meant to say Bennett's.

Maybe the only thing that won`t break.

[DonV]

How true Sandy!! I had Lencos on my 22 Pathfinder, the best thing about them was the actuators were easy to replace, a couple of screws, splice the wires and prepare for the next replacement. I would buy two when I found a good deal, nice to have a spare at home. Plus the old ones looked right at home in the garbage can.

[Offshore Asset]

So after giving it some thought. I think I might be skipping the bracket and going for a traditional motor on transom approach. I don't want to pour as much money into it as I originally thought. And I scored a sweet $1,000 Aquasport 17 with a 1998 Johnson 115 that I plan on using until I finish the seacraft. Then running that 115 on the Seacraft until I put on a new motor. Luckily the Johnson is really clean and it is a 25" shaft, plus it weighs around 350lbs. I have the transom done. It just needs the stringers finished and a floor.

[Terry England]

Originally Posted by Offshore Asset

....... Then running that 115 on the Seacraft until I put on a new motor. Luckily the Johnson is really clean and it is a 25" shaft, plus it weighs around 350lbs......

Offshore, Here is what I think you will see with the correct prop -
Miminum planing speed: 12-15 MPH
Max. Speed: (no tee top, light load) 32-34 mph
Max. Speed: Tee top, 6 tanks, dive gear etc.) 28-30 mph
Fuel burn: 6 GPH @ 4,000 rpm = 22-24 MPH (4 MPG)
Miami to Bimini - 15-18 gallons.
You will not have a race boat, however that is the weight motor the 20' SeaCrafts were originally designed for
- so just sit back a R-E-L-A-X.

Check with Fr. Frank, Tiny, Capt Terry, Denny, Tom Paris and others to see what they think. End to end that crew would have surpassed Magellan's circumnavigation with their 115 HP powered SeaCrafts. Lots of data with them to "adjust" my preliminary input.

[Bushwacker]

Originally Posted by Offshore Asset

So after giving it some thought. I think I might be skipping the bracket and going for a traditional motor on transom approach. I don't want to pour as much money into it as I originally thought. And I scored a sweet $1,000 Aquasport 17 with a 1998 Johnson 115 that I plan on using until I finish the seacraft. Then running that 115 on the Seacraft until I put on a new motor. Luckily the Johnson is really clean and it is a 25" shaft, plus it weighs around 350lbs. I have the transom done. It just needs the stringers finished and a floor.

That's a good choice and great match for the boat . . . those old V-4's are tough simple motors; ran an old cross-flow (1975 vintage) on my boat for 31 years and it NEVER left me stranded the whole time I had it. Just make sure it rev's about 5500 @ WOT; a 13 3/4 x 15 SST prop worked good for me. I put about 2000 miles on it on a bunch of trips to the Abacos. Used to carry about 65-80 gallons of gas, and a couple of weeks worth of groceries. With a big load in cabin and light motor, I could plane at about 12 mph and ride through a 2-3' chop sitting down! Cruised at about 20 kts (22-23 mph) @ 4500 for hours on end at about 8 gph. Seemed to consistently average about 2.8 mpg carrying heavy loads. Your motor is a looper, so should put out a little more power and be more efficient. (They were rated at powerhead instead of prop in 1975!)

[TomParis]

I dont know what pitch prop I have, but my 20' CC with a FICHT 115 will do 28-32 MPH with 3 adults and 30 gallons of gas in the tank.

not sure of my fuel burn, but I can play for a couple of hours in the bay around the St Marks river and only burn 5-6 gallons of fuel.

I cant wait to repower with a E-tec 115!

[Offshore Asset]

The boat will be mainly used in Miami and the Keys just running around and live baiting the edge. As much as I love speed, this may not be the boat to do it in. I'll build it as light as I can so I really maximize performance. I already built the transom out of Coosa, and I cut out the liner and will probably run nida-core for the floor while still raising it 3 inches. I also want to build a shroud for the motor. And I have a small console out of an 80s 18 Seacraft. Half the fun is planning it after all

[Bushwacker]

Originally Posted by Offshore Asset

I'll build it as light as I can so I really maximize performance. I already built the transom out of Coosa, and I cut out the liner and will probably run nida-core for the floor while still raising it 3 inches. . . .

The inner liner is there for a reason . . . it adds a lot of torsional stiffness to the hull, which a CC needs, since it doesn't have a cabin top or full height bulkhead to tie the hull sides together! A lot of guys install balsa or foam core against the hull sides to stiffen up the hull when they remove the liner. Adding some bulkheads under the raised deck will also add some torsional stiffness.

[Offshore Asset]

Originally Posted by Bushwacker

The inner liner is there for a reason . . . it adds a lot of torsional stiffness to the hull, which a CC needs, since it doesn't have a cabin top or full height bulkhead to tie the hull sides together! A lot of guys install balsa or foam core against the hull sides to stiffen up the hull when they remove the liner. Adding some bulkheads under the raised deck will also add some torsional stiffness.

I agree there. The hull is very thin. Could I get away without a coring material and doing a layer or two of 1708? I am thinking that with the bulkheads I put in under the deck, and a big front bulkhead for the anchor locker, it should be pretty stiff. The floor will be going directly to the hull sides as well as maybe 2 vertical supports on each side. I've seen balsa used as coring. Just uneasy about putting wood back into the boat after I took out so much of it that rotted. Any other suggestions on foam coring materials for the hull sides? Is divinycell the standard nowadays?