how much power do I needed?

[amadaeus]

hello
I recently purchased a '76 20'seacraft and it has an old 200hp evinrude. I was wondering if a 150hp yamaha would be enough for this boat w/ some load? Mods are already starting!

thanx!

[catman115]

Fishtale, My 20' sefari had a 135 merc on the back and that was plenty of power. A 150 should be just fine power wise but without getting into the whole transom rebuild thing. My opinion is that most of the sea crafters here enjoy thier boats for fishing rather than racing. Just my .02

[Michael Vezzosi]

Catman, purchased my '79 20 w/200 Blackmax. Seatrialed beautifully in Tampa. Towed to H.H.I. and blew 100 feet from the dock! What a surprise! A brand new head gasket! Three years later, after a very expensive rebuild that never ran right, I repowered w/'99 John. 175.. Carburated and dependable. Not sure of topend, but sufficiently strong throughout all ranges. Only about 90 hours on it today and not sure of fuel economy. Don't fish it like I used to, either. Usually a crew of four, large cooler of adult beverages, and seems the longer the day, the average speeds consistently grow. Not sure how I'd repower today, but I'm very happy with what I did back then. Hope this helps. Vezo.

[pogden]

My 1978 Master Angler originally had a very tired 1979 Evinrude 150, it ran about 35-38 mph. I am rebuilding the transom and have a 2001 Merc 200 EFI almost ready to go.

I think anything from a 135 to a 150 would be fine on a older 20" transom. If you want to rebuild the transom and raise it to 25" and maybe go with a bracket then you could probably go with the heavier(more HP and/or 4-stroke)motors.

[RAHIM NAHIM]

What is the ball park top end speed for a 20ft SC with a Mercury 200 hp engine.

[amadaeus]

thankx for all your responses it helps alot. My transom was rebuilt and raised to 25" according to the previous owner, but I think i'm going to repower it with a 1996'-98' yamaha 150 efi if ppossible. This old 200 evinrude goes thru gas like water so I think I'll be better off with a 150 EFI or maybe if I can dish-out $7500 I'll go with a DF140 hp Suzuki!

[Capt Chuck]

What is the ball park top end speed for a 20ft SC with a Mercury 200 hp engine.

Count the number of "NO-SEE-UM's" that slammed between your teeth/divided by tear drops X number of times your ears flapped against the side of your skull in 5 mins at WOT

[Fr. Frank]

You need about 115 horsepower. A 135 or 150 V6 won't go real fast, but the motor won't strain as hard.
On the other hand, there's the old theory that you should put enough HP on your boat to scare your wife into staying home while you go fishing with the guys. If that's where you are, then a 225 would be about right. Figure somewhere around 60 mph with a 2 stroke Optimax or HPDI.
I have even seen a SeaVette with old T-275 Jag block Mercs up in OC, MD. (One of the lower units was blown out)
But then, where would you go to need that kind of speed.? [img]/images/graemlins/cool.gif[/img]

[John R]

I have even seen a SeaVette with old T-275 Jag block Mercs up in OC, MD. (One of the lower units was blown out)
But then, where would you go to need that kind of speed.? [img]/images/graemlins/cool.gif[/img]

I have a 23 that had twin 235s on it and while I never ran it with those engines I'm confident it would have gone fast on 110 gals but not far [img]/images/graemlins/blush.gif[/img]

[TUGBOAT]

Wan'na Reason fo'Mo speed !
The boat juz' at the spout is juz' a lil UNDER POWERED ! Bet He wished He bought those Quad 300's instead of the 115 His wife said He could have !!

Gotta 150 Merc. Carb on My 20' Master angler . I'll go back to at least a 175 next time(200 Mariner when purchased),Lost some speed When I Added Xtra glass to the Girl.Juz' like it When I Need it ,down Here!
Scream'n Reels' [img]/images/graemlins/smile.gif[/img]