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Old 11 February 2013, 03:11   #1
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Inversion proofing

Hello

I am interested to know what modifications are carried out to the RNLI outboards to make them inversion proof.
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Old 11 February 2013, 04:26   #2
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Go and Talk to Barrus in Bicester.
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Old 11 February 2013, 06:11   #3
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In summary, trim/tilt lockout, ignition cutout, flap to seal air intake, there was a bowl to drain & refill petrol but not sure if still the case on the newer engines, and a lot of sealing of the wiring looms, etc. The water ingresses the hood but not the block.

Takes about 2 weeks work IIRC?
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Old 11 February 2013, 06:12   #4
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+1.

I believe they have (had?) a lever that does 2 things - opens a "dump valve" on the bottom of the carb(s) and opens a drain port on the cylinder head.

Idea being you pull the lever, open the cyls, dump the water mixed fuel & crank to purge. Then close lever & carry on. There may be PRVs on the cyls as well - it's been a while (might be 10+ years) since I was at the talk.....
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Old 11 February 2013, 14:25   #5
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Different mods for the different engines..... (Evinrude, Yam 2 & 4 stroke)

But if its the smaller (D Class etc) Mariner (Tohatsu) units you are interested in (?) Uncle Al on this forum is a chap who may be able to assist you with more technical questions.....He did a lot with these units whilst at Barrus
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Old 11 February 2013, 14:56   #6
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There are 2 main systems:- Dry & Wet. Dry system seals the tray, has a flap on the exhaust so water does not enter via exhaust when inverted. Pies from carb overflows to direct fuel away from electrics (not required on more modern engines) lid has either a pendulum or air/electronic flap to seal lid & engine cuts off at 90 degrees as a mercury switch is fitted. Engine only needs bulbs primed to restart. Wet system allows water inside the engine & carbs need drained & plugs removed and water expelled before righting. Near impossible to do in anything other than flag calm. Kevin Mole on IOW is probably the best Dry system chap at the moment. Barrus best for wet systems. RNLI, also do a great job but money is no object with them.

Hope this helps.
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Old 11 February 2013, 14:57   #7
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Pipes from the carbs, ruddy predictive text.
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Old 11 February 2013, 17:27   #8
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Well, i used to build and test these, the Barrus Version lets the water in Its called PIRS (Post immersion Restart System) Just a few drain taps on the carbs and thats about it. you have to take the plugs out pull it over 15 times by hand open the drain taps pump the primer till you see fuel coming from the outlets. Plugs back in, re prime and pull like a bugger. If it doesnt start do it all again.
The other version which i spent about 3 years testing is the fast PIRS which is much better. You dont take off the top cowl to do it. There is one lever that opens the carb drains and also opens valves in the cylinder head and opens the transfer ports in the block. Do that, and either hit the start button of 15sec or pull start for 15 sec, slam the lever shut and away you go. Its pretty good, but will only allow about 3 capsizes in one go, after that the plugs get badly contaminated with seawater/oil mixture. There was an early version in which you had to open the transfer port valve as well as the head valves but we got that done to a single lever for the 2nd generation. Only available on a few models as you need to have an engine with a seperate cylinder head cover, such as the 25/30hp and the TMC 40/50hp. Its a great mod but very expensive to build as the engine needs a new cylinder head making, cam box arrangement making, water proof electrics etc etc.
Not sure how Yam do there system but im sure it stops the water from getting in rather than the de watering system.
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Old 11 February 2013, 17:33   #9
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Interesting stuff. I recall reading the yam 4 Stokes on the newer Atlantics only needed a cut of switch and cowl flap (ish) as the seal around the cowl to the tray was so good water didn't find it's way in very easily at all.

Prob speak nicely to an ILB crew and they may well explain it all. ;-)
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Old 12 February 2013, 02:23   #10
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The original inversion proofer was Buzzard Engineering on the IOW. They began with the RNLI and then the North Sea standby industry had an enormous amount of 55 Yamaha's proofed for use around Oil Installations. Through the 80's RGIT/Maritime Rescue International, sent their engineer to Australia to build a system for them to use. The mantle was taken on by the Dutch KNZHRM/KZHRM before North & South merged to become KNRM. They used an electronic solenoid (dry) system as the pendulums would close in short steep seas, there was a handle to re-cock the system, then all you had to do was prime the bulb and you were off again. They stopped proofing their engines when they realised that after training in Stonehaven (MRI) the crews were no longer capsizing. The last set of pendulum lids left Stonehaven fir Freshwater Rescue in the early 1990's. Price of proofing and codings have gone a long way to killing the proofing off as in a capsize under say cat 3, the boat itself becomes a liferaft and effectively the crew has to call for assistance, boats are also much bigger with greater power, making a capsize less likely in experienced hands. Finally engine design fashion changes regularly, meaning a new design of hood requires a new design of proofing. That said in a rescue situation, I would rather have it than not...
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