Top speed (sceptre I/O)

floorboy · #1 02-02-2014, 02:03 AM

I was just curious (I get bored in the winter) I've never seen a thread where somebody stuffed a monster motor in one of these things. Is there a recommended top speed before you end up chine walking or some other catastrophic event happening?? And what would it take to get there, or at least slightly below there??

Just curious, all the I/O's I've seen run in the high 30's/low 40's. I know mine will never be a speed demon with the top but always looking for more. Installing a 300hp 350 now.

Entourage · #2 02-02-2014, 08:28 AM

My brother has a 76 Sceptre with 383 stroker and a bravo 1 and we got that up to 44 kts on the gps, no chine walking we just couldn't steer it. We had the factory power steering and it just couldn't handle it, too much slack in it. If we had better hydraulic steering we could have buried it cause we didn't have it WOT yet.

Entourage · #3 02-02-2014, 08:33 AM

Lotta fun here

Islandtrader · #4 02-02-2014, 09:51 AM

2 things same motor as above on my 21 will top out at 50mph.

The yellow Seavette with the BB in it will top out at over 60 mph...

FLexpat · #5 02-02-2014, 11:49 AM

Quote:

Originally Posted by Islandtrader

2 things same motor as above on my 21 will top out at 50mph.

The yellow Seavette with the BB in it will top out at over 60 mph...

Seavette has same hull but a different liner, cap etc - he has 502 HP, says 65 mph -
http://www.classicseacraft.com/commu...light=seavette
I know it isn't a linear interpolation but...
If the stroker (~350 CS HP) does about 44kts (50 mph)
Seavette (502HP) does 65 mph
it takes about 400 HP@ crank to get to 55 mph
400HP is the spec limit on a base Bravo 1.

This is why the 5.7 I have is probably temporary

bigeasy1 · #6 02-02-2014, 06:40 PM

Quote:

Originally Posted by floorboy

I was just curious (I get bored in the winter) I've never seen a thread where somebody stuffed a monster motor in one of these things. Is there a recommended top speed before you end up chine walking or some other catastrophic event happening?? And what would it take to get there, or at least slightly below there??

Just curious, all the I/O's I've seen run in the high 30's/low 40's. I know mine will never be a speed demon with the top but always looking for more. Installing a 300hp 350 now.

Uh Oh, what are you planning?
I know this isnt what you asked, but you should be able to get in the low 40's with your new power, even with the top up.My motor is only a 260 hp with an Alpha drive, and my top speed is about 39 mph, with the big sail of the top up and the radar arch, fuel, kicker, as well as as a couple of us heavy weights and all tackle.

I saw your restoration pics on the gla site, you're doing a beautiful job, post them up here, the more boat porn the better.

Entourage · #7 02-02-2014, 08:26 PM

These boats are not designed to go over 50mph the weight displacement isn't right for that amount of speed. They need more stern weight. These boats are an all around great rough water boat. They can take the power no problem just not the type boat for those speeds. This is why I guess they have the Seavette more bow and you drive more towards the stern.

floorboy · #8 02-03-2014, 01:25 AM

I drove the old entourage one day. It handles way different than mine does. It trims the nose down much harder/easier. Mine I am almost at full trim tab to get any nose pressure down. I don't know why, I thought with the big top on it it would be a little more nose heavy but it's not.

The motor/drive combo I'm putting in ran out right at 50.0 in the boat I took it out of. It was a foot shorter boat without a top and an aluminum prop. I'm hoping I can clear 40 no problem. Thinking about starting to collect some bravo stuff and dumping that 420hp 383 in it. I like tinkering and if I sell off some of the stuff I have I could pay for the motor or drive easy..... Always thinking.

I have a buddy with a 21 foot warrior that thought he was big chit until he tried to follow me one windy day.

all I saw was the bottom of his boat. He beat me the next day but he only runs 46 or so so I wouldn't take much to beat him on a flat day either. Fuel consumption is not a major concern as you can tell.

Entourage · #9 02-03-2014, 08:00 AM

Keep in mind Entourage only has a 57 gallon fuel tank that makes a difference as well. As to some others sceptres and tsunamis have 75 gal plus.

bigeasy1 · #10 02-03-2014, 02:53 PM

Rod,
Its a moot point now as you are repowering but did you try changing ths prop?, on the original power/drive.?

Its funny how the exact same boats with very similar power and drive systems can perform very differently.
My Tsunami that is almost identical to yours in weight and power and same high canvas topl hops up on plane very fast, and rides very level.In nice water conditions I rarely have to touch the 12x12 dropfin tabs.

If its blowing head on, a small adjustment to the tabs brings the bow down pretty quick.I have only a 52 gallon fuel tank, that sits about amidshjp in the boat.
One would think it would be harder to keep the bow down with less fuel weight.Go figure.