Classic SeaCraft Community  

Go Back   Classic SeaCraft Community > Recovered Threads

Notices

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 12-27-2019, 11:17 PM
Jared Jared is offline
Recovered
 
Join Date: Apr 2018
Posts: 47
Default 1986 20' SF with a Merc 150 4S performance numbers

I looked around a lot for numbers like this when I was looking for new power, found a lot of people asking similar questions but a lot less that got a detailed answer to it. Maybe this will help someone with their decision making down the line. I know lighter power is preferred on these hulls and I would tend to agree, but since I was doing all the work myself I tried to take a lot of steps with rebalancing weight try minimize the change in CG. A little information about the setup in general:

- 1986 20' Seacraft SF
- 2019 Mercury 150 4 stroke (25" shaft)
- Engine mounted in middle hole
- Mercury black max 13 1/4" x 17p 3 blade prop (p/n 48-77344A45)
- Original floor height
- Fuel tank reduced to 52 gallons, rear edge of tank slid 30" forward of front edge of in floor livewell compared to original tank (70 gallons)
- Factory center console replaced with a 10" narrower custom one with a cooler in front instead of cooler/storage seat molded to front of original console.
- Rear edge of console moved 6" forward of rear edge of original console location
- 2 batteries moved inside console from rear hatches.

Boat sits in water with water level touching deck scupper outlets in transom. I have check valves installed inline for the deck as well as the hoses crossed port to starboard so it minimizes water on the deck if someone is standing in the rear corners.

RPM/GPH/MPH
2500 3.5 15.8
3000 4.3 23.7
3500 6. 28.8
4000 8.2 32.4
4500 11.2. 37.2
5000 41.0
5300-5400ish 44.8

all the numbers up to 4500 are with 2 adults and 3 kids on board, 40 gallons of fuel. 5000 and up were just me, half tank of fuel. I have to scroll through my smart craft gauge to get to GPH, I didn?’t want to take a hand from throttle and steering to do that at that at those speeds.
Reply With Quote
  #2  
Old 01-14-2020, 08:10 PM
hillcharl hillcharl is offline
Member
 
Join Date: Jun 2009
Location: Charleston, SC
Posts: 34
Default

Those are pretty good numbers with a 4S
__________________
'89 SeaCraft 20 CC 200 Evinrude
Reply With Quote
  #3  
Old 01-18-2020, 08:13 AM
cdavisdb cdavisdb is offline
Senior Member
 
Join Date: Feb 2006
Location: Sarasota, FL
Posts: 1,056
Default

My written performance numbers are long gone, but the speed/rpm numbers look very close to my old 20 Seafari's performance with a 150 Black Max 2 stroke. I bet your fuel economy is far better than mine.
Reply With Quote
  #4  
Old 01-19-2020, 09:25 AM
Jared Jared is offline
Recovered
 
Join Date: Apr 2018
Posts: 47
Default

Quote:
Originally Posted by cdavisdb View Post
My written performance numbers are long gone, but the speed/rpm numbers look very close to my old 20 Seafari's performance with a 150 Black Max 2 stroke. I bet your fuel economy is far better than mine.
Did a 143 mile round trip for an overnighter a few weeks ago up the ICW, burned 30.2 gallons. Took 10 hours total between slow zones and areas we could run faster. Very happy with that.
Reply With Quote
  #5  
Old 01-20-2020, 10:11 AM
captbone captbone is offline
Member
 
Join Date: Feb 2003
Location: Long Island
Posts: 73
Default

I would recommend trying other propellers. I believe you are leaving a ton of performance on the table with that existing propeller.

I would recommend trying either

17 Pitch Enertia
or
17 Pitch Mirage Plus

When you see the size difference between you existing prop and one those I suggested, you will be surprised.
Reply With Quote
  #6  
Old 01-20-2020, 03:55 PM
Jared Jared is offline
Recovered
 
Join Date: Apr 2018
Posts: 47
Default

Quote:
Originally Posted by captbone View Post
I would recommend trying other propellers. I believe you are leaving a ton of performance on the table with that existing propeller.

I would recommend trying either

17 Pitch Enertia
or
17 Pitch Mirage Plus

When you see the size difference between you existing prop and one those I suggested, you will be surprised.
I?ll give one of these a try for sure, thanks for the recommendation. I was getting close to the end of the build, I?m sure most of you know how at that point my budget was blown and just about doubled! This was what got me on the water in my budget at the time and I have been so happy with it I haven?t revisited yet.

Been wanting to keep a spare prop/hub/nut on the boat, when I can move to something like you suggested my current one will become just that
Reply With Quote
  #7  
Old 01-20-2020, 05:10 PM
DonV DonV is offline
Senior Member
 
Join Date: Jul 2004
Location: Apollo Beach or Islamorada
Posts: 3,488
Send a message via ICQ to DonV
Default

"I?m sure most of you know how at that point my budget was blown and just about doubled!"

Welcome!! There are many of us that have lived in that world!!
Reply With Quote
  #8  
Old 01-26-2020, 09:27 AM
Bigshrimpin Bigshrimpin is offline
Senior Member
 
Join Date: Dec 2002
Location: Onset, MA
Posts: 2,712
Default

Quote:
Originally Posted by captbone View Post
I would recommend trying other propellers. I believe you are leaving a ton of performance on the table with that existing propeller.

I would recommend trying either

17 Pitch Enertia
or
17 Pitch Mirage Plus

When you see the size difference between you existing prop and one those I suggested, you will be surprised.
I agree but 2 adults and 3 kids on a 20 w/full fuel is a big load.
Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 01:37 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
All original content © 2003-2013 ClassicSeacraft