Reply
 
Thread Tools Search this Thread
 
Old 11 August 2006, 22:14   #11
Member
 
Country: UK - Wales
Town: swansea
Boat name: Too Blue
Make: BLANK
Length: 8m +
Engine: Suzuki DT225
Join Date: Mar 2004
Posts: 12,791
Have you seen what happens to most 4 strokes when water gets into the air intake? Bent valves and conrods. I saw a 2 stroke outboard the other day merrily bubbling away under water until it stopped - they had it running again in 1/2 hour.
__________________

__________________
codprawn is offline   Reply With Quote
Old 12 August 2006, 06:05   #12
Member
 
Country: UK - England
Town: cornwall
Boat name: nothing
Make: rib eye 430
Length: 4m +
Engine: tatsu 50
MMSI: 666
Join Date: Mar 2006
Posts: 1,916
Quote:
Originally Posted by codprawn
Have you seen what happens to most 4 strokes when water gets into the air intake? Bent valves and conrods. I saw a 2 stroke outboard the other day merrily bubbling away under water until it stopped - they had it running again in 1/2 hour.
Merily bubbling away underwater untill it stopped ?? get real and think . Both engines will damage due to hydraulic action of the water it just depends how fast the thing is going when it goes under . Any engine drawing a lung full of H2o at full chat is dead .
__________________

__________________
ian parkes is offline   Reply With Quote
Old 12 August 2006, 07:45   #13
Member
 
Country: UK - Wales
Town: swansea
Boat name: Too Blue
Make: BLANK
Length: 8m +
Engine: Suzuki DT225
Join Date: Mar 2004
Posts: 12,791
Quote:
Originally Posted by ian parkes
Merily bubbling away underwater untill it stopped ?? get real and think . Both engines will damage due to hydraulic action of the water it just depends how fast the thing is going when it goes under . Any engine drawing a lung full of H2o at full chat is dead .
Not so on 2 strokes because they have ports instead of valves. Granted the engine wasn't going flat out though - was probably just on tickover as the driver's foot was no longer on the throttle!!!
__________________
codprawn is offline   Reply With Quote
Old 12 August 2006, 10:32   #14
Member
 
Country: UK - England
Town: cornwall
Boat name: nothing
Make: rib eye 430
Length: 4m +
Engine: tatsu 50
MMSI: 666
Join Date: Mar 2006
Posts: 1,916
Quote:
Originally Posted by codprawn
Not so on 2 strokes because they have ports instead of valves. Granted the engine wasn't going flat out though - was probably just on tickover as the driver's foot was no longer on the throttle!!!
The ports are the reason for the extra problems water gets to the Big ends little ends and main bearings then gets above the piston . Its all much harder to get out and does damage as the engine is starved of oil as you turn it to get it started .
Ports or valves damage still happens if its revving .
__________________
ian parkes is offline   Reply With Quote
Old 16 August 2006, 19:11   #15
Member
 
Country: UK - Scotland
Make: Ribcraft
Length: 5m +
Engine: 90hp
Join Date: Aug 2006
Posts: 380
Quote:
Any advice as to the liklihood of restarting a 4 stroke engine after capsize?

I've dunked a small 2s engine twice (both times running). 1st time boat tured over and engine got swamped - was running when it went under and ended up full of water.

2nd time I was wearing the kill chord and the engine bracket broke on my little Avon 9ft. Engine fell of the back, stopped because of kill chord and was left dangling by the secondary attachment (ie rope). Got it back to shore and it started. The inside of the cowling was pretty much dry as there was obviously an air bubble inside the cowling preventing any water to get in (air vent holes are on underside). I did drain the fuel and re-fill as there was water in the fuel tank.

I guess whether the engine gets flooded depends on many things - position of crank when it stops (whether water can get into cyl via exhaust port or whether exhaust valve is open on 4str), whether the engine is running when it goes under (I assume if the boat inverts, engine will stop due to kill chord).

4 strokes are notoriously fussy about positioning of the engine to prevent oil draining out (ie which side you lay them on if transporting with a car). After a capsize, it's likely the sump oil is everywhere so may be a bad idea to try and start them without a good check over first.

The RNLI do (or certainly did) mod's to their 2-strokes to make them start after a capsize...
__________________
al40 is offline   Reply With Quote
Old 16 August 2006, 19:26   #16
Member
 
Country: Other
Town: Stanley, Falkland Is
Boat name: Seawolf
Make: Osprey Vipermax 5.8
Length: 5m +
Engine: Etec 150
Join Date: Mar 2006
Posts: 3,688
Quote:
Originally Posted by al40
4 strokes are notoriously fussy about positioning of the engine to prevent oil draining out (ie which side you lay them on if transporting with a car). After a capsize, it's likely the sump oil is everywhere so may be a bad idea to try and start them without a good check over first.
I only have experience with upside down vehicles but I would think that it would be OK as long as it was righted fairly quickly?

Vehicles usually are, the problems come when you leave them upside down for a long period (hours or even overnight) and the oil creeps past the piston rings etc, then you try to start it up and bang, hydraulic the engine due to the oil in the cylinders.
__________________
BogMonster is offline   Reply With Quote
Old 16 August 2006, 19:34   #17
Member
 
Country: UK - England
Town: cornwall
Boat name: nothing
Make: rib eye 430
Length: 4m +
Engine: tatsu 50
MMSI: 666
Join Date: Mar 2006
Posts: 1,916
there is so much talk of 4 strokes draining the oil out . If one had been rolled then it would be a good idea to check the oil on the dipstick . A 4stroke would need to be left on the wrong side for quite a while for a problem to occur .
A to make sure water hadn't got into the sump
B to make sure there was enough oil in it .

The entire contents of sump oil would be unlikely to find its way out of the engine , if it could it would all be pushed out while the motor was running .
If water entered through an open valve it can still only get above the piston ,
A the engine will iether not turn over due to hydraulic action of the water , in this case removing plugs etc will sort it out
B the water will be purged through the valves

If its any conselation , last year I made a mount for my canadian canoe and used a Honda 2.2 . My mate also got the same outfit . and he recently tested it for wet starting .

last week he told me he had capsized the canoe . The kill cord stopped the motor I guess , he said he drained the carb and it started easily . It was upside down for long enough for him to get to the bank of the river 5 mins I guess no oil was lost and no water got into the oil .

What modifications do the RNLI do to make an engine start easier after drowning ?
__________________
ian parkes is offline   Reply With Quote
Old 17 August 2006, 07:12   #18
RIBnet admin team
 
Poly's Avatar
 
Country: UK - Scotland
Boat name: imposter
Make: FunYak
Length: 3m +
Engine: 2 stroke YAM 20 HP
MMSI: 235089819
Join Date: Sep 2005
Posts: 10,114
Quote:
Originally Posted by ian parkes
What modifications do the RNLI do to make an engine start easier after drowning ?
Turbo diesel has explained it here in another thread before
__________________
Poly is offline   Reply With Quote
Old 17 August 2006, 08:58   #19
Member
 
Country: UK - England
Town: cornwall
Boat name: nothing
Make: rib eye 430
Length: 4m +
Engine: tatsu 50
MMSI: 666
Join Date: Mar 2006
Posts: 1,916
Quote:
Originally Posted by Polwart
Turbo diesel has explained it here in another thread before
Interesting stuff which also backs up my experience that a 2 stroke is a major problem to start when the crankcase has water in it . In fact many older 2 stroke off road bikes used to have a drain plug in the crankcase ,
Montesa and bultaco I think
__________________
ian parkes is offline   Reply With Quote
Old 24 August 2006, 17:53   #20
Member
 
Country: UK - England
Town: NE
Boat name: RedGazelle
Make: Gemini GRX420 SIB
Length: 4m +
Engine: Mariner 40 2s
Join Date: Nov 2004
Posts: 105
Thanks for the replies-

Will stick with what I know for now...

From experience, I can restart the 2 stroke Mariner after 5 minutes upside down in surf (without PIRS kit). Will wait to learn from other peoples experience of swamped 4 strokes and look forward to seeing which engine the RNLI specify to replace the Mariner 40hp 2 stroke on the D-Class ILB (SIB).

Thanks

Ed
__________________

__________________
Ed the Duck 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 17:05.


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