20' HP ratings

[JWB]

Anyone know what a early 1070s 20' is rated for? 1974?

[Ikan Besar]

http://www.classicseacraft.com/20SFSpecifications.htm

[Fr. Frank]

My 1972 20' Seafari OB model has a small metallic OEM decal under the helm that gives the serial# and maximum capacities. It says "Max HP: 240"
I run an older 150 Merc V6, and can reach 50 mph in the right conditions. It originally came with a '73 Chrysler 120 hp, and planed easily with that motor, with a top speed of 25 mph.

On the other hand, I had a customer back in 1984 who bought a new 20' SeaCraft CC hull, and requested from the factory a new sticker raising her max OB HP rating from 175 to 250, and the Seacraft factory did, in fact, send her the revised decal. We then installed one of the big-block 3.4L V6 Mercury 250 HP outboards on her boat with a hydraulic jack-plate. We got a top speed of 62 mph.

We also sold a used 23' SeaCraft SeaVette OB model placarded for 600 hp Max, and rigged with twin 225 Mercs that same year. Top speed on that one was 73 mph, but measured only by AirGuide speedo using a paddle-wheel pick-up.

How much power do you need? The fish aren't that fast [img]/images/graemlins/grin.gif[/img]

[Bigshrimpin]

JWB - Keep in mind that 1970's and 1980's motors weighed a lot less than most of todays outboards. For example a New Mercury Verado 200 weighs 650lbs vs. a 1978 Merc 200 which topped the scales at a lean 340lbs. 650lbs on the stern of a 20footer will sink the boat, so try to keep the stern as light an possible (400 - 425lbs).
The 20 seacraft also starts to chinewalk at speeds above 45mph, so there is not much point in powering the boat with anything over 200hp.
I think a 150hp would be perfect match for the 20.

[Michael Vezzosi]

My 1979 MA is stamped at 200 hp. Currently running a 1999 Johnson 175 carbed. Redid transom from inside in same year, prior to finding this site. Could not afford bracket at that time. Extremely trimmed (just before overheating alarm), myself (155 lbs. just after bad breakup) and low fuel would like to think I am nearing 50. SS prop but not sure of size. 54-5600 revs. 200 horses would have been great but at that time Ficht technology was very bad. Different degree block for 200-225. Very satisfied with present setup. Have not experienced any type of chine walking with this hull, BUT, on the otherhand, I have a 15 Whaler with an '05 Yammie 60 4 stroke and a jack plate! This is not for inexperienced boaters, but if you want to try chine walking, this is the rig!

I'd like to feel the Seacraft walking but I definately do not have the power for that.

BTW, speed freaks, some new video of the Jersey Speed Skiffs added to www.speedkiffs.com, under Boats by Name. Rebounder, first skiff to unofficially break 100 mph! Pretty impressive though not sure I'd like to try it. Also, two videos of wrecks, 70 to 90 mph, if you click on Links, and go to Jersey Speed Skiffs (forums) and scroll down to bottom (videos). The site owner wrecks at 90!

Thats all for now, hope it helps. Vezo, Part II. JS-04 senti-MENTAL-value.

[Joe R]

My 1970 cc is rated for a 140 hp ob...the dealer that sold them in my area back then put them out with 88hp outboards.I have had 115 yaham. 120 evinrude and now 150 evinrude carb. the 150 is great on this boat is uses less gas than the smaller outboards because I dont have to push it to get the same speeds....Joe R 1970 Seacraft cc

[timd]

My 1974 placard stated 175 HP max. I am running a 2001 [img]/images/graemlins/shocked.gif[/img] Evinrude Ficht 175, and it hauls a$$.

[Fr. Frank]

I echo BigShrimpin concerning chine walking on the 20' Seafari. I have had mine at 43 kts, and it began to chine walk at about 39-40 kts. Very gentle, but definitely there. Proper trim becomes a big issue when a deep-V hull begins to walk. I have seen what happens when a 26' Scarab center console with a single 250 Yamadog chine walked into a snap turn and barrel roll at about 50 mph. Not a pretty site.

If you've got counter rotating twins, it's suddenly not a problem, though. [img]/images/graemlins/grin.gif[/img]