Reply
 
Thread Tools Search this Thread Display Modes
 
Old 05-08-2015, 04:23 AM   #11
Admiral
 
mmwjr's Avatar
 
Join Date: Feb 2012
Location: Perry Hall, Maryland
Posts: 5,397
Default

I use boat tests in magazines of similar boats ton weight, beam, and length.

From what I have seen the 4.3 is around 8 GPH in most applications. Since you have 2 double that plus add some margine.

A single big block typically is 15 GPH.

Even using the big block GPH for twins you should have enough fuel to make the trip and back.
__________________

__________________
Mike
mmwjr is offline   Reply With Quote
Old 05-08-2015, 10:35 AM   #12
Lt. JG
 
Join Date: Nov 2013
Location: NY
Posts: 26
Default

I have a 98 2800 scr with twin 4.3's i usually get 2mpg at 3200-3300 rpms.
__________________

Lawnman is offline   Reply With Quote
Old 05-08-2015, 11:22 AM   #13
Admiral
 
mmwjr's Avatar
 
Join Date: Feb 2012
Location: Perry Hall, Maryland
Posts: 5,397
Default

Quote:
Originally Posted by Lawnman View Post
I have a 98 2800 scr with twin 4.3's i usually get 2mpg at 3200-3300 rpms.
Is that per engine or the composite of both?
__________________
Mike
mmwjr is offline   Reply With Quote
Old 05-08-2015, 01:56 PM   #14
Moderator

 
Join Date: Apr 2008
Posts: 3,554
Default

Quote:
Originally Posted by Mothers Day View Post
around 3,000 - 3400 which should give me approx 25 mph. (ocean)
3000 - 3400 is actually a big range because it spans the tipping point where the boat wants to jump on, or fall off of plane.
The approx. speed at 3000 is going to much different than at 3400.
My point was that 25 mph at 3k is not reasonable.

Quote:
Originally Posted by Mothers Day View Post
No. I'm seeing about 22-23 at 3300.
Slightly lower rpm with following sea. My boat has almost no additional weight added since I haven't really outfitted her yet.
Here you're actually getting 22-23 at 3300. It will be lower than the target 25 when you drop down to 3000. In fact, you haven't loaded the boat yet. My numbers are real-world numbers with water, fuel, gear, clothes, food, coolers, dinghy, portable generator, dinghy outboard, beer (yes, I feel 3-5 30 packs warrant its own weight calculation thank you very much for not judging our lifestyle).

I fact, I think I estimated 18-20 at 3k which these numbers are closer to corroborating than refuting.

Get the boat loaded up and your projected numbers are going to go down.
__________________
Leave me alone, it's Boating Season!!!
shrew is online now   Reply With Quote
Old 05-08-2015, 01:58 PM   #15
Moderator

 
Join Date: Apr 2008
Posts: 3,554
Default

What size, blad and pitch props are on the boat now? I went to a 4 blade FWD, 3 blade AFT @ 22.5 pitch and it made a huge difference. The 3blad 24p on the boat made the boat a dog. 24P is NOT the stock prop pitch.
__________________

__________________
Leave me alone, it's Boating Season!!!
shrew is online now   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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Powered by vBadvanced CMPS v3.2.3

All times are GMT. The time now is 01:06 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.