Finally Fishing!

[Fr. Frank]

Got the boat out Saturday for a real fishing trip, not just a test ride for a different propeller.

Got into a variety of sharks over several hours. A Lesser Atlantic hammerhead about 15 lbs. A shortfin Mako about 18-20 lbs. 2 small Lemon sharks 5-7 lbs each. And one small shark of uncertain lineage under 2 lbs. All were released.

Drifting in 18-20 ft about 15 miles offshore in the Gulf using bottom lines and floating toplines out, with whole sardines on Kingfish rigs on the top, and grouper rigs with stingers baited with with whole small squid. And frozen shrimp on 8lb spinning single rigs jigged off the bottom.

The Mako hit the topside bait on 30 lb. test, jumped several times, and put on quite a show. Everything else was taken off the bottom. The 8lb shrimp rig brought in the tiny shark.

Coming in, we got hit by a very nasty thunderstorm, lightning everywhere, rainfall of over 3" an hour, and easterly winds of 25 mph, and gusting higher. Everyone but my son and I went into the cabin. The two of us got soaked. So did the camera

[McGillicuddy]

Right on! Bummer about the camera... What prop did you end with and what are your perf. numbers?

[Fr. Frank]

Propeller was inadequate. It is a Mercury Trophy Plus 4 blade 13.75"D x 21"P 4-blade, part # 48-825934-21 .
Propeller has 4 1/2" ventilation holes in the outer hub to allow the motor to spin up to high rpms quickly.

Max speed with average load of 6 people, full fuel, plus fishing gear, etcetera, was 33 mph @ 5150 rpms.
(Same prop produced 34 mph @ 5300 rpms with one person, lightly loaded.
Cruise with this average load was 26 mph @ 4500 rpms.

BAD NEWS: I was unable to keep the boat on plane below 4200 rpms/22 mph because of propeller ventilation causing a loss of thrust.
Time to plane was nearly 12 seconds.

On two previous tests, with just myself onboard, the prop performed okay. But the right prop also has to perform well with heavy loads and in adverse conditions. I think this prop, with the ventilation holes plugged, would have been perfect with a 115 hp Optimax on my hull. Unfortunately, I have a 90 hp Optimax.

I have a pretty good idea what prop style/size I need. I just can't afford it.
I think a 13"D x 18"P 4 blade with moderate, slightly progressive rake, and moderate cupping on the backside of the blade, and little cup at the blade tips would be about right.
I really like the design of the SCD4 by PowerTech. It can be seen on the last page of the "D Class" prop catalog from Powertech. PowerTech D Class props

[McGillicuddy]

Where do you put 6 people on a Seafari?
I feel crowded with 2 and don't think I could fish w/ more than three.

What accounts for the ability of a heavily loaded 90hp to swing a 4-blade 21 pitch prop to 5150rpms while I can only swing a 21 p 3-blade MWC Vortex 4400 rpms and get only 5000rpms in a 17p Black Max. Could my tach be way off or is it the torque curve or gearing of the respective motors, mine being a 115 "tower of power"? I got 35 mph (30 knots gps)out of the 17p black max with old gas. A 2knot improvement over the old 21p Vortex

Also, you had steered me to the black max geometry - I'll eventually pickup an ss MQF from PowerTech unless you're thinking the 3 or 4 blade SCDs are better way to go...have you run a Yamaha style semi-cleaver like the SCDs on your Seafari? Are they theoretically a faster or easier to turn wheel than the black max shape? Better stern-lift?

[Fr. Frank]

Where do you put 6 people on a Seafari?

2 teenage girls (1 mine) suntanning on the cabin topside deck, 1 kid (not mine) sitting on the front of the portside lounge seat reading a book, my wife and I and 1 kid (mine) fishing.

What accounts for the ability of a heavily loaded 90hp to swing a 4-blade 21 pitch prop to 5150rpms while I can only swing a 21 p 3-blade MWC Vortex 4400 rpms and get only 5000rpms in a 17p Black Max.

I have a 2.33:1 gear ratio. You probably have a 2.0:1 gear ratio. My 90 also actually produces 106 hp at the prop. Pre-'84 115 Merc inline-6 motors produced 115 hp at the powerhead and about 105 hp at the prop.

Also, you had steered me to the black max geometry - I'll eventually pickup an ss MQF from PowerTech unless you're thinking the 3 or 4 blade SCDs are better way to go...have you run a Yamaha style semi-cleaver like the SCDs on your Seafari? Are they theoretically a faster or easier to turn wheel than the black max shape? Better stern-lift?

I really like the Black Max props. They just work well. No getting around that. The MQF from PowerTech and the Mirage Plus for V6 motors is variation of that same geometry.
No, I have never run a semi-cleaver like the early Yamaha SWS props on my Seafari. I have run them on a '76 19' Robalo with twin '85 90 hp Yamahas. They provide lots of stern lift.
As I understand it, the PowerTech SCD4's should theoretically be an ideal prop for a SeaCraft Seafari, with the right diameter and pitch, and right height. But I haven't got the money to test one. My last Powertech prop was custom-ordered/custom-made OFS3 for about $700, and I got it with the proceeds from a 16' Blazer bass boat I sold.