Thread Tools Search this Thread
Old 06 June 2010, 06:55   #1
Country: UK - England
Town: Oldham
Boat name: Aqua Vitae
Make: Ribcraft 4.8
Length: 4m +
Engine: Yamaha 75hp
MMSI: 235115057
Join Date: Jul 2005
Posts: 331
Tune the engine or change the prop?

Once again, I am consulting the vast knowledge of the gurus!

I have a 3.6m Tornado with a 25hp Mariner marathon 2-stroke on the back. It will give me about 23kn on a flat day, fully loaded with 3 on board. It sometimes takes a while to plane, and I have to move all the crew to the front to get it on the plane at times.
Most of the time, I am cruising but I sometimes pull an inflatable or wakeboarder.

I'm wondering whether to tune up the engine or change the prop. I guess I'd need one prop for cruising and one for towing, though I may be wrong!

Prop details:
Diameter - 10 3/8
Pitch - 11
Material - Alum
Blades - 3

Thanks guys and girls!


A RIB is for life, not just for Christmas.
Northern Tim is offline   Reply With Quote
Old 06 June 2010, 11:16   #2
Country: UK - England
Town: Sussex
Make: Ceasar Surfcat
Length: 4m +
Engine: Tohatsu 50hp
Join Date: May 2006
Posts: 105
That engine is easy to tune to 30- Just remove the restrictor/gasket from between the carb/engine, refit gasket from a Tohatsu 30(or make one yourself to suit the larger opening), then advance the timing by 5degrees by altering the timing advance rod. It makes a notable difference.(It should do anyways being a 20% hike in power)
Easyrider is offline   Reply With Quote

Thread Tools Search this Thread
Search this Thread:

Advanced Search

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

Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 11:45.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, vBulletin Solutions, Inc.