Ski blows up - clear those fumes before starting

[Bigal6030]

On Saturday thick black smoke filled the air above the marina next to mine. I later found out a jet ski blew up literally. The driver hit the start button and accumulated gas fumes ignited. The explosion blew the top of the ski and the rider 15' in the air. The rider suffered a broken back. Does anyone bother to pull their seats before starting or is there a blower set up for skis.

[K447]

The owners manual (probably for every make and model) encourages the rider to lift the seat and inspect the engine compartment prior to starting the engine. Sniff for fuel fumes, and also look for anything that might be visibly wrong.

Fuel leaks can happen. Even on newer model watercraft with four stroke engines.

That said, when I read about a PWC exploding it often involves an older machine, often with carburetors.

My suspicion is that as the machines get older the fuel systems are not always well maintained. Old fuel hoses, loosening hose clamps, general wear and tear from vibration, heat, corrosion. Same with the battery electrical system.

And older watercraft are less likely to be professionally serviced. The (second, third, fourth) owner will be doing their own maintenance work, or not doing the maintenance work. The only way to make an older watercraft safe and reliable is to do the work, and spend the money, to keep it well maintained. Skimp on that and the risk of something bad happening increases.

Right now, somewhere, there are PWC with fuel fumes trapped inside the enclosed hull, and a potential source of sparks ready to ignite the fumes, should the Start button be pressed.

Personal Watercraft have a specific exemption from the Coast Guard regarding the bilge blower fan. Because a PWC must be able to float (for a while) while upside down in the water, PWC do not have forced ventilation for the engine compartment.

It only takes a minute to lift the seat and sniff around BEFORE you touch that Start button. Someday that minute might save you from having a really bad day.

[TimeBandit]

Does anyone bother to pull their seats before starting or is there a blower set up for skis.

Not going to lie - this threat crosses my mind nearly EVERYTIME I hit my start button. I do practice lifting the seat at the ramp. In fact, this is when I line-up my battery cut-out switch (custom installed) which is obviously mounted inside the hull. Usually take a good whiff when I toggle the switch.

However, since I do also fish from this craft, it's not always conducive, safe, or otherwise awkward to lift a seat while adrift in deep open waters, not to mention waves. Restarting after having been at anchor for the last hour - this is when I really worry the most about this threat.



Blower? Funny you ask. So to help mitigate the time when I cannot lift the seat, I actually have a blower installed (again ÔÇô custom DIY project) a few years back. My practice has been to flip the blower on while I wrap up things, aka pull-in the anchor, secure gear. That's at least a good minute or two of ventilation.

The blower is screwed directly onto the inner hull liner, at the bottom of the stbd canaflex hose. I had to cut that hose end shorter by 4 inches to make room for the blower. The blower basically sucks air in from the stbd vent, and escapes mainly out the port vent, AND some places around the seat seal ÔÇô which is handy, as I can smell the hull odors, permitting me to better assess the air-quality without lifting a seat.

The bad-news, is that I'm on my 2nd blower. Even the marine-grade ÔÇ£boatÔÇØ blower couldn't handle the salt environment after one year. This new blower, not only a different brand . . . I also took some extra measures to caulk and better water-proof areas which I noted from the first failure.

[nmpeter]

as usual, I can top that....

Two seasons ago one of my regulars asked me to winterize his skis, as usual, I've been servicing these two Polaris 1200's for the last ten years.

I always finger wag him about filling the tanks on the skis before he puts them into storage after his last outing of the weekend

Well when I picked up the skis, the tank on one of them was empty, the other full.

I pull the seat off and blamo, the hull has 6 inches of gasoline in it. The fuel tank was leaking.

Had I hit the starter button I would have been a dead man for sure.

leaking tanks is a serious threat on older skis, always pull the seat and give it a once over, before it's too late.

The other story was a ski that had been invaded by pack rats over the winter, they had chewed into the air intake and nested right against the blower, the whole thing was corroded beyond reason, I just told him he needed a new supercharger, and an ^&^*^&*^&*^* exterminator

boat blowers are cheap, and it's pretty common for them to fail after a season or two if used often, as they should be. My pal with the boat shop has a shelf full of em

[TimeBandit]

Yup ... you won the topper-award

Back on the blower topic... something I did note, is what insures the blower itself does ignite the situation?? Many state gas-safe etc... but being, my observation, typical brushed DC motors, one really needs to insure the mfr ratings are genuine and certified before trusting.

[K447]

... what insures the blower itself does [not] ignite the situation??

Many state gas-safe etc... but being, my observation, typical brushed DC motors, one really needs to insure the mfr ratings are genuine and certified before trusting.

Not just the air extraction fan, all the wiring and switchgear should be ignition proof.

This is why you will only find sealed electrical connectors throughout a PWC wire harness. No exposed contacts or wire ends. Yes, the wiring also needs to defend itself against water and corrosion. But it also must not ignite fuel fumes, should they be present. *

A lot of 'marine grade' electrical stuff sold for use on boats (switches, fuse panels, etc) is only intended for installation in well ventilated areas, not in an engine compartment where fuel fumes may be present.

* somehow the PWC industry still thinks it is OK to have exposed (in other words, not ignition proof) metal connections at the battery, the starter motor, start solenoid studs, and the engine end of the negative battery cable. Any of these can generate sparks if the cable end works loose or corrodes.

[nmpeter]

That explains why the kill switch for a mid 90's Seadoo has an Msrp of over $100 it's fully sealed

If memory serves the remove seat before fueling stickers started appearing on some 2000 m/y skis

[Myself]

I explain to my customers how important it is to check under the seat. I literally count seconds out loud as I show them how to remove the seat, grab the engine and see if it's solid ( motor mounts), visual inspection, and sniff for fumes. When I put the seat back on any machine it's less than 30 seconds. Then it's allright to fire it up and make sure it's going to start. You don't want to be "That Guy" at the launch, on a hot day, when everybody is trying to get in the water, and His ski won't start.

[K447]

- how important it is to check under the seat...

Bumping this thread up as a reminder to everyone.

Always lift the seat and inspect the engine compartment before starting the engine for the first time each day.