Reply
 
Thread Tools Search this Thread
 
Old 29 March 2004, 08:07   #1
Member
 
Country: UK
Make: Ribcraft
Length: 4.8m
Engine: Mercury F60 EFI
Join Date: Dec 2003
Posts: 89
Teething Problems

Hi,

I lauched my Ribcraft 4.8 on Saturday and it was superb! Boat was really easy to handle and within minutes I felt comfortable putting in the tightest spots! The engine was superb and sounded awesome! However, I did have one problem...

When on the plane, I got a lot of spray coming up over the transom. This spray was mostly directed away from the boat, but some water was coming in. I'm no expert but it clearly wasn't right. How can I stop all this transom spray? (It was both sides of the outboard leg but worse on the side with the elephant trunk, which was in the up posistion). I can only describe it as two 'fountain like' sprays of water coming up from the transom area. Can anyone tell me how to correct it? Is it to do with incorrect trim?

Thanks,

Robert
__________________

__________________
Robert1 is offline   Reply With Quote
Old 29 March 2004, 08:19   #2
Member
 
Pete7's Avatar
 
Country: UK - England
Town: Gosport
Boat name: April Lass
Make: Moody 31
Length: 9m +
Join Date: Aug 2001
Posts: 4,850
Rob hi,

Assuming the engine is the right length for the hull and has been trimmed correctly so the prop is horizontal then it is likey that the engine hasn't been fitted at the right height and you are getting spray from the front anti cavitation plates. Try jacking the engine up a hole.


Pete
__________________

__________________
Pete7 is offline   Reply With Quote
Old 29 March 2004, 08:29   #3
Member
 
Country: UK
Make: Ribcraft
Length: 4.8m
Engine: Mercury F60 EFI
Join Date: Dec 2003
Posts: 89
Ribcraft fitted the engine...Surely they woudnt have done it wrong?
__________________
Robert1 is offline   Reply With Quote
Old 29 March 2004, 08:39   #4
Member
 
Country: UK - Scotland
Make: HumberOceanOffshore
Length: 8m +
Engine: Volvo KAD300/DPX
Join Date: Oct 2002
Posts: 4,962
Quote:
Originally posted by Robert1
Ribcraft fitted the engine...Surely they woudnt have done it wrong?
__________________
JW.
jwalker is offline   Reply With Quote
Old 29 March 2004, 09:43   #5
Member
 
Country: UK
Make: Ribcraft
Length: 4.8m
Engine: Mercury F60 EFI
Join Date: Dec 2003
Posts: 89
Thanks for the suggestion, Pete. I'll have a word with Ribcraft. Anyone else got any ideas?
__________________
Robert1 is offline   Reply With Quote
Old 29 March 2004, 10:38   #6
Member
 
Country: UK - England
Town: Midlands
Make: Nautique
Length: 6m +
Engine: PCM 5.7l
Join Date: Oct 2003
Posts: 1,082
Theres not really anything else down there that might cause that.

Once the engine has been lifted, if that is the problem expect an extra few knots top speed
__________________
simmons0 is offline   Reply With Quote
Old 29 March 2004, 10:53   #7
Member
 
Country: UK
Make: Ribcraft
Length: 4.8m
Engine: Mercury F60 EFI
Join Date: Dec 2003
Posts: 89
I have spoken to Jason at Ribcraft and he has diagnosed the problem:

'Our transoms have a greater angle than most for increased grip and planing ability when loaded, I.e. you can get the engine trimmed in further. Hence most of our hulls when planning run with the engine trimmed slightly, if you trim the engine out slightly the spray will go away.'

This makes sense and I will try it next weekend. Roll on Saturday!

Robert


P.S.
Pete, refering to your post, this would explain why the prop would not have been horizontal to the waterline.
__________________
Robert1 is offline   Reply With Quote
Old 29 March 2004, 14:40   #8
Member
 
Country: UK - Wales
Town: Milford Haven
Boat name: Various
Make: Commercial
Length: 10m +
Engine: Screw / Voith / Jets
Join Date: Sep 2002
Posts: 791
Send a message via MSN to Alex Brown
Hello Robert,

I had a similar (what I thought was a) problem as you when I first got my boat...... Assuming the trim would be about right if I left the needle in the middle, and with the engine looking pretty level I thought that was all there was to it, but no

Image on the right shows when I first got the boat, and had level trim.... image on the left shows trim at the 3/4 mark which is my standard cruising level.

In my case, lifting the engine (not an easy task) did not prevent the water coming over the transom, and it also only increased my top end by half a knot or thereabouts, so the engine went back down to where it was originally.
Attached Thumbnails
Click image for larger version

Name:	engines.jpg
Views:	353
Size:	43.2 KB
ID:	4983  
__________________
Flickr Photos
Youtube Videos
Alex Brown is offline   Reply With Quote
Old 30 March 2004, 03:46   #9
Member
 
Country: UK
Make: Ribcraft
Length: 4.8m
Engine: Mercury F60 EFI
Join Date: Dec 2003
Posts: 89
Alex, so trimming the engine away from the transom solved your problem? The spray shown the the pic on the right is what I have been getting.

Robert
__________________
Robert1 is offline   Reply With Quote
Old 30 March 2004, 07:11   #10
Member
 
Country: UK - England
Town: Great Harwood, Lancs
Boat name: Tigger II
Make: Bombardier Aerodeck
Length: 3m +
Engine: Tohatsu 25HP
Join Date: Jul 2001
Posts: 626
Hi folks

I always calibrate my trim gauges so its shows level when the cavitaion plate is level with the hull.

Just get a long length of wood and set the engine cavitaion plate parrallel with the hull using the wood as a guide.
Just hold the wood along the hull and trim the egine until it lones up with the wood.

Next most trim sensors can be adjusted, often onlt two srews to loosen, turn the sensor till the trim gauge reads level and tighten the screws.

After a while you stop using the trim gauge and run with what "feels right" for the conditions. but at the start i found the gauge useful.
On my previous 4.8 the engine trim made a hugh difference to the handling & performance of the RIB.

Regards Gary
__________________

__________________
Garygee is offline   Reply With Quote
Reply

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 10:25.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.