Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 18-11-2019, 05:11   #1
Registered User

Join Date: Apr 2019
Posts: 232
Highfield

We have a Highfield 340 with a Yamaha 20hp 4 stroke. With just two of us, we fly but with 4 people we can't get up on step, the motor bogs down, and the stern just rides low.

The prop is a 9.25x12.

I've ridden in other RIBs with MUCH smaller outboards that easily got 5 of us on step.

Is this an outboard issue (it's new), prop issue, or expectation issue?
__________________

crayiii is offline   Reply With Quote
Old 18-11-2019, 05:43   #2
Registered User
 
Hesti's Avatar

Join Date: Nov 2018
Location: North Germany
Boat: 29 ft
Posts: 129
Re: Highfield

Weight distribution, engine trim and outboard shaft length can all be a factor.

Weight distribution - more weight forward? Anyway, play around with it.

Engine trim - trimming the shaft as close to the stern as possible may help to get on the plane.

Shaft length - the anti cavitation plates of the shaft should be pretty much on the same level as the underside of the hull in that area. If anything, the anti cavitation plates might even be a bit higher, say an inch, than the underside of the hull in that area.


If the above does not help, looking into the prop might.
__________________

Hesti is offline   Reply With Quote
Old 18-11-2019, 05:57   #3
Registered User

Join Date: Feb 2009
Posts: 2,153
Re: Highfield

12" seems like to much pitch. I have good results with a 4 blade with low pitch. 8 or 9 inches. I am more concerned about getting on plane with the load that I am top speed. You 11' boat should plane with 4
motion30 is offline   Reply With Quote
Old 18-11-2019, 06:21   #4
Moderator
 
JPA Cate's Avatar

Join Date: Nov 2011
Location: aboard, cruising in Australia
Boat: Sayer 46' Solent rig sloop
Posts: 17,099
Re: Highfield

The first thing I'd look at would be pitch. Changing it made the difference for us between planing with 4 and not. If the angle at the stern of the drive leg is correct, then moving weight forward a bit may help.

Go to the Yamaha folks and discuss an alternate prop that will meet your needs better, and keep the spare for when the new one fails or is damaged.

Ann
__________________
Who scorns the calm has forgotten the storm.
JPA Cate is offline   Reply With Quote
Old 18-11-2019, 06:29   #5
Registered User

Join Date: Feb 2009
Posts: 2,153
Re: Highfield

A hydrofoil device on the cavation plate works wonders as well
motion30 is offline   Reply With Quote
Old 18-11-2019, 07:27   #6
Registered User

Join Date: Oct 2009
Posts: 751
Re: Highfield

I can tell you what worked for me in getting the dinghy to plane, although I was dealing with a much smaller outboard and dinghy than you and the my approach may not scale. I had a 10 foot wooden floor Achiilles with a 5 hp two stroke Nissan. There were two of us aboard and we could not get the thing to plane regardless of what we did. I called up Nissan and asked for a higher pitch prop and put it on. And while it took longer to get up to speed, the top in speed was enough to plane the thing and once on plane we could back off the throttle and shift our weight back astern.
__________________

lancelot9898 is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Highfield Dinks? Info/Opinions Wanted! BILLYBYEPOLAR General Sailing Forum 32 04-06-2019 17:32
For Sale: Highfield lever Jim Cate Classifieds Archive 2 23-06-2014 22:50
For Sale: highfield lever and corsair rigging $200 sywhynot Classifieds Archive 2 20-03-2014 16:51
For Sale or Trade: Corsair F-28R standing rigging and highfield levers bkibler Classifieds Archive 2 10-07-2013 06:08
For Sale: ABI Forestay Quick Release Highfield Lever Boatguy30 Classifieds Archive 5 30-11-2012 21:19

Advertise Here


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 17:29.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
×

ShowCase vBulletin Plugins by Drive Thru Online, Inc.