Seven Marine 627 hp outboard
 

All the discussion about best fit for 23' Sceptre.......twins 150's, 250, 300 hp

I'm thinking ONE of these and the boat becomes a " Super Sceptre."

Ok so at a bit over 1,000lbs somewhat heavy, but proper transom can handle.

Performance............now this is the fun part:
Cruise.....................maybe 45mph at 4,000 rpm ?
Fast cruise...............maybe 55mph at 4,500......
WOT.......................maybe 70mph +.....wide open, trimmed and tab'd just right.

How would it ride ? I'm thinking wow.

My 5.7 Bravo 1 I/O is just over 1000 lbs so I'm thinking the balance wouldn't be very far off. 627HP just might get it fast enough to chine walk a bit... I'm thinking more like 80+ if it doesn't start dancing first.

The 2009 Seacraft 26's were designed to go 65 with twin 250 Verados.

Humm..... I gained approx 8 mph with 50 extra hp....so let's just figure 15 mph per 100 hp.
With 300hp, I believe Scepter runs about 50mph. Since the rule of " diminishing returns " kicks in, speed increase per 100 hp will yield less.... but, fair enough even at 10mph per 100, 80mph seems possible !! ( assuming of course the hull can handle)

In sailboating, there's a term called " hull speed" meaning no matter how hard the wind blows, that hull will only reach approx X mph.

Seems the older 23 was a hull capable of speed.

I have seen pictures of 23's with twin 225's and twin 250's and the owners tend to say that after 65 they get scary as hell. The one guy with twin opti 225s said he got his up to 68 and that was with 8 people on board. He also said that with just him he never got passed 63. The weight kept it in the water and kept it from walking all over the place. You will never go safely over 70 in this hull with out major modifications. A motor like this would work good for an half throttle cruse of 60 plus but past that the top end would be wasted. Now from stop to 60 with the handles dropped would be one hell of an ride.

I think kmoose actually had twin 250s on his and he may can give you some actual experience. Im just going off what I have been told.

I had twin 225's on a bracket on a 23 SF. I was at three-quarter throttle at 60. Doodlebug had twin 250s on his Sceptre.

x2!


Bgreene - 23 seacraft is a kick ass fishing boat . . . no need to try to make it into something it's not ;) If your objective is to go fast (above 55 - 60) there are much better hulls to work with than a 23 and power plants that have a superior power to weight ratio than seven marine engines.

http://www.donks.net/wordpress/wp-co...oads/donks.jpg


http://www.allisonboats.com/content/...-boats-top.png


see the nice pad on the Allison ^^

Doodlebugs rig was so stern heavy he had to power load
getting off the trailer.

Previous owner of my current sled......

Great discussion - I am running twin 2.5L Mariner 175 hp on a Gilbracket my 1973 Tsunami. It's been up to 60 - engines keep the boat weighted down - but it's a bit fast for the hull. Runs nice at 45-50, like the twins in a big following swell for stability.

Forgot to mention a much improved ride with a pair of 12" bennett trim tabs

BIG SHRIMPIN' ...... this is for fun, it's winter, what else we have to do ?

Of course it's a fishing boat and rigged best 250-300.

Know what a " sleeper car " is ?

WOW....how fast ?

I had a Seavette with twin 2.4L merc 200s (360 lbs ea.)with 225 carbs spread 25" & built for racing. Previous owner cited top speed at 68mph on radar gun. Had some textured racing paint and 12 x 12 bennetts. I sold it because I knew I couldnt afford to run it:eek:

It would def be the most expensive engine ever put on a Seacraft , 85K plus.

"Good morning, Charter Lakes Insurance, this is Judy how may I help you?"

I'm DonV and I would like to increase the "agreed value" of my 1978 Seacraft.

"Let me look at your policy, hummm I see we have an agreed value of $25,000, what would you like to do?"

I want to raise it to $100,000. I just installed a new engine. It's a Marine7.

"Never heard of a Marine7. What's the HP on the new engine?"

Judy it's a bad ass 627 HP. I just had it installed for $85,000 and I want to cover that along with my Classic SeaCraft.

"Well Mr. DonV I see your boat is rated for 235 HP and don't you think 627 HP is a bit above that?

Just a little bit, but Danny, Brian and Ken all have new 300 HP engines and I wanted to out-do them.

"One moment let me check"

OK, I'll wait.

"DonV, we have cancelled your insurance and will be sending you a refund. Good bye."

click.

Now that's funny!! Was that a real call?...LOL!!

too funny Don!!! HAHAHAHA:D.

Isn't that what you are sleeping in when your wife finds out you spent 85K on a outboard motor?

Yes, it is. Or will be. And parked someplace else.

I'll have to check with him but it wasn't as fast as some other numbers posted.

Here's a pic from THT showing a 627 being installed on a custom built carbon flats boat.

Someday you have to tell us about the boat bitch.

I`m starting a website called ODYC.
Online Dating Yacht Club.
I feel it is my duty to help the afflicted find like minded life partners.

You have fun on the boat every weekend and you get to keep the house, the boat,
and all your stuff.

No Jim, just me thinking what it would be like to try and insure my 23'er after adding a Zuke 300 or an eTec 250HO, never mind the extreme Marine7. I can hear the insurance agent saying, "you do know your engine is worth more than your SeaCraft?"

No doubt us SeaCraft folks are a bit crazy!! :)

Headhunter is that flats boat being built for the same guy who drove his boat into the restaurant in Tampa or St Pete last yr?

Right now a Barker 26 is being built in Sarasota. All Carbon Fiber and a 627 on the Transom.
Custom Bob's Marine jack plate too. 200k bay boat.

an 1100lb badonkadonk 627 isn't gonna help the speed, draft, or performance of a bay boat.

Two 335hp 3.1L Merc Pro XB's from Simon motorsports or even a pair of 300promaxs weigh 200lbs less and cost 1/4 of the price.

They say it can't be done.....well if that was true, our guys wouldn't have walked on the moon!

I say a pair of worked 2.5 280's with 260 electrics turning 10,000 rpm @325+HP each and less than 800lbs would be even lighter! :)

The pro xb's probably would be more reliable tho...

:d



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Bgreene - It's the motivation that I am questioning. No one is saying it couldn't be done, but the purpose of a bay boat is to venture into shallow water inshore. You are defeating that purpose by installing that GIANT HEAVY motor, which is working directly against that goal.

If your goal really isn't to go into shallow water with the "bay" boat, but rather to achieve high speed, then there are many other power options for 1/4 of the cost. Those engines above (300promax, PRomaxXB, 260/280's) will push that hull a LOT faster than one 1100lb 627 badonadonk marine engine.

so my feeling is that since this engine neither allows you to achieve goal 1 of bay boat or goal 2 of maximizing your speed/performance . . . what is the real motivation?

Maybe the dealer network for Seven marine where this guy lives is really good and he has access to reasonably priced parts and labor.

Hummm........personally I'm thinking....

1. speed - the 7 Marine engine WILL push faster top speed than a 300hp.

2. function - I don't believe that bay boat's being rigged for poling shallow water, rather just to
experiment towards having an extremely fast rig, capable of easily cruising at fast speed at lower rpm, and a wild top end speed.

3. purpose - fun, experimentation, to be the first smaller rig with the monster motor !
Whoever is paying, I assume has the money to burn, and play.....

I'd categorize this discussion as fun related, not too serious. Hope none of the SeaCraft purists find it offending... after all, it's boating, not actuary work, and I don't wear a bow tie when I go boating !! :)

bgreene - TWO . . . as in Quantity 2 . . . or 1+1 = 2 or TWIN PromaxXB 335hp (335hp + 335hp = 670hp) weigh approx 900lbs combined (about 450lbs each) at 1/4 of the price of seven marine 627.

BIG......... I doubt the guy who owns the boat with 7 Marine cares about the price.

Ferrari 458 more that twice the price of Corvette, but does guy who buys Ferrari care ?

It's about doing it, not carefully measuring all aspects of feasibility.

That's it for me, if it bothers you.....call the owner and talk em' out of it.

http://static.autoblog.nl/images/wp2...-fight-001.jpg

This thread reminds me of a scene from zoolander.

https://www.youtube.com/watch?v=3Huc47Dqsg8

Good grief charlie brown...you've gone stark raving mad !

People all water vessels have a designed in hull speed in displacement mode. The way to increase over that is to get as much of the hull out of the water. ie ride bow wave. Faster than that you become air born and a hard to control missile. George. Ps cant change physics.

This was a friend of mine that had 30+ years of offshore racing experience. His 27 magnum was close to 70mph WOT. Going fast in a boat can get you killed.

http://www.offshoreonly.com/forums/m...fe-killed.html

what about the merc 400R. alot less weight, money, and still leave a zuke 300 boat like it's tied to a wall?

Don't worry, Suzy got a new ride out soon that will be able to cut the dock line... and it won't be a 2.6 liter toy. ;)