Reply
 
Thread Tools Search this Thread
 
Old 08 November 2004, 01:19   #1
Member
 
Country: USA
Town: Bellingham, WA
Make: Bombard
Length: 4m +
Engine: Mercury 50HP
Join Date: Nov 2004
Posts: 4
Q - Help with water over the transom

Greetings. I have a Bombard C5 (4.8m), with a 2001 Mercury 50hp two-stroke. At full throttle there is a "waterfall" of water coming over the transom, just below the steering unit into the boat. This is a substantial amount of water. To help alleviate the problem, I trim the motor up, but if I hit a large wave the engine revs and there is a large loss in power. (I assume the prop has cavitated, as the problem is corrected if I slow down, and/or trim the motor back down)

This afternoon I raised the motor one hole hoping this would correct the problem, but it didn't.

Any help would be appreciated.

Thank you.

Adam Horsman
__________________
Adamhorsman is offline   Reply With Quote
Old 08 November 2004, 08:04   #2
Member
 
Country: UK - England
Town: Chelmsford/Anglesey
Make: Avon SR/RibLite 3.1m
Length: 4m +
Engine: Honda 30hp/Yam 8hp
Join Date: Jul 2003
Posts: 970
That's an interesting coincidence - my brother's got a Bombard Aerodeck 3.8m with a 25hp Yamaha 2-stroke, the maximum size engine for this boat, and he has exactly the same problem at full throttle. As yet his dealer has been unable to effect a solution (sounds familiar ).
__________________
Phil Davies is offline   Reply With Quote
Old 08 November 2004, 15:09   #3
Member
 
Kernow Buoy's Avatar
 
Country: UK - England
Town: Cornwall
Length: no boat
Join Date: Oct 2004
Posts: 1,518
Hi Adam,
My last boat was a C5 and I had that same problem, I found that putting your least favourite child right in the bow does help a little although the screams are a little intrusive! ( This is British sense of humour - honest!!)
But seriously weight forrard does help, additionally I also had hydrofoils fitted to the outboard and again found an improvement with the waterfall situation.
Hope this helps.
Jeff
__________________
Kernow Buoy is offline   Reply With Quote
Old 08 November 2004, 15:29   #4
Member
 
Country: USA
Town: Bellingham, WA
Make: Bombard
Length: 4m +
Engine: Mercury 50HP
Join Date: Nov 2004
Posts: 4
water

Thank you for the responses. Prior to this outboard I had a newer Tohatsu 40hp, which I had no problems with at all. (water, or mechanically) I almost wonder if I need to bump back down to a lighter/smaller outboard. According to Bombard, the boat is rated for up to a 60hp outboard.

As to the weight in the bow, I had two sets of double steel scuba tanks, plus decompression bottles, and other miscellaneous gear. I would venture to say this is at least comparable to one small child, possibly even two.

Adam
__________________
Adamhorsman is offline   Reply With Quote
Old 08 November 2004, 15:43   #5
Member
 
Country: UK - England
Town: Farnborough
Boat name: Narcissus
Make: Cobra
Length: 7m +
Engine: Optimax 225
Join Date: Jul 2003
Posts: 2,281
With the engine trimmed 'normally', where is the cavitation plate in relation to the bottom of the boat?
__________________
Matt is offline   Reply With Quote
Old 08 November 2004, 20:13   #6
Member
 
Country: USA
Town: Bellingham, WA
Make: Bombard
Length: 4m +
Engine: Mercury 50HP
Join Date: Nov 2004
Posts: 4
water

The cavitation plate is ~3-4 inches below the bottom of the boat. (trimmed normally)

Adam
__________________
Adamhorsman is offline   Reply With Quote
Old 08 November 2004, 21:26   #7
Member
 
Country: UK - England
Town: Ipswich
Boat name: Obsession
Make: ORKNEY PILOTHOUSE 20
Length: 6m +
Engine: SUZUKI 70
MMSI: 235024496
Join Date: May 2004
Posts: 390
I think you'll find that is to low,it should be level with bottom of the hull or higher.If you raise it you will improve top end speed and may correct your problem.
__________________
Never be scared of the sea but always respect it.
www.aquasnaps.co.uk
Wayne Rogers is offline   Reply With Quote
Old 08 November 2004, 23:11   #8
Member
 
Country: UK - England
Town: Farnborough
Boat name: Narcissus
Make: Cobra
Length: 7m +
Engine: Optimax 225
Join Date: Jul 2003
Posts: 2,281
I agree.

Quote:
Originally Posted by Wayne Rogers
I think you'll find that is to low,it should be level with bottom of the hull or higher.If you raise it you will improve top end speed and may correct your problem.
__________________
Matt is offline   Reply With Quote
Old 09 November 2004, 03:31   #9
Member
 
Country: USA
Town: Bellingham, WA
Make: Bombard
Length: 4m +
Engine: Mercury 50HP
Join Date: Nov 2004
Posts: 4
water

Thank you very much. I appreciate all of the responses.

Adam Horsman
__________________
Adamhorsman 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




All times are GMT. The time now is 14:50.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.