need more engine room blowers???

[seatotaler]

I just had a survey (Canadian) done on my boat for insurance purposes and the surveyor "recommended" that I "must" add 2 more engine room blowers. I have twin 454 crusader gas engines and one 6.5 Onan gas genset in the engine room. The engine room is about 9 ft. x 7 ft. The boat is a 1985 37 Trojan and it has always had one blower, as far as I can tell. I had it surveyed 5 years ago and the surveyor never recoomended more blowers at that time. I'm sure over the boat's life time it has had many surveys, for insurance update purposes or when it changed hands. Adding two more blowers makes no sense to me.
I just had a new gas fume sniffer installed within 60 days prior to the survey and the surveyor knew that. The rule of thumb is to let the blower run for 4 minutes before firing up the engines. The sniffer will sound if there are any fumes 24/7. So if the sniffer doesn't sound before firing up the engines, in effect I would think it's mostly a formality running the blower assuming the sniffer is operating properly. But it's always a good practice to be overly safe and run the blower anyways.
All that two more blowers is going to do is clear the engine room air faster but not more efficently, given the 4 minute rule of thumb as suggested in the owners manual. In theory some people might think since two more blowers have been added, then they only have to run the blowers for about a minute and a half. Bad idea of course but in theory that would make sense.
He also suggested I run the end of the hoses as close to the bottom of the engines as possible. I didn't think that gas fumes linger down low like propane. If there was a preference to the open end of the hose location, I would think it would be placed close to anything that might make a spark, like plugs, or coil.
Also he didn't mention what cfm's the additional blowers should be. He didn't even check what cfm's my existing blower is.
Where is the surveyor getting his information from to make "must do recommendations" from? I would suspect that the surveyors "rule book" should be available on line somewhere.
Thanks to all who might have any insight towards this.

[rslifkin]

1 blower is probably not enough airflow to meet the standards (or be safe) unless it's a really big blower. I'd want at least 2 personally, and my similar boat (with a somewhat larger engine room) has 3.

Gas fumes do sink like propane, so the intakes need to be in the lower third of the engine room. And the fume detector doesn't sound for small quantities of fumes, only once it's at 20 percent of the explosive threshold typically. So you still need to run the blowers before every startup.

Ideally, physically inspect before turning the blowers on before the first start of the day. You'll smell fumes long before the detector will go off, and going down there is a good opportunity to check fluids before start anyway. I also strongly suggest an in person inspection after fueling (before turning on blowers).

[BlackHeron]

Dreading the eventual insurance survey.

ABYC regulations should be published if they expect people to "obey" them on boats made decades before some industry group decided to make up their own "voluntary" rules and arm-twist everyone into playing their shady game.

[Randy]

I wouldn't blankly accept the surveyors assessment. Though I'd say take the time to look up the specific regulation. It would be logical that a certain number of air exchanges are required to take place in a given amount of time. Now I'm curious and will look up the US regulation.
And here is a link to the cfr and table for air exchange calculation for gasoline engine compartments.

https://www.law.cornell.edu/cfr/text/33/183.610

I imagine Canada has something similar.

[seatotaler]

I think it would make sense if when a surveyor makes a "must do recommendation" that they follow it with a quote from the regulations that supports their recommendations.
I would think that in this case there would have to be a relationship regarding the cubic measurement of the engine room and the cfm rating of the blower(s) and the diameter of the hose used ie: 3 or 4 inch. Then a formula would produce a specific number. That number would be compared to a number set by the regulations for the same amount of cubic measurement of an engine room to determine if the blower(s) met the standard.
Maybe the blower that I have is a monster blower, equaling 3 typical blowers. Maybe the boat owner might go out and buy 2 tiny inline exhaust fans and put them in 2 inch dryer vent tubing, since no cfm requirements were specified.
There should be more than just speculation or hunch on the part of the surveyor.

[seatotaler]

Originally Posted by Randy

I wouldn't blankly accept the surveyors assessment. Though I'd say take the time to look up the specific regulation. It would be logical that a certain number of air exchanges are required to take place in a given amount of time. Now I'm curious and will look up the US regulation.
And here is a link to the cfr and table for air exchange calculation for gasoline engine compartments.

https://www.law.cornell.edu/cfr/text/33/183.610

I imagine Canada has something similar.

Thanks Randy, But I don't know what I'm reading in col.2 ? Is col.1 refering to length of boat? and I have no idea what col. 3 is telling me either. ???

[Jahwork]

Hello fellow Mariners,

To answer your questions, when I open the link Randy provided, it has a description of the columns directly below.

Column 1 is volume of the space to be ventilated, in this case engine room size in cubic feet

Column 2 is blower capacity rating in cubic feet per minute.

Column 3 is total system output in cubic feet per minute

Hope that helps in your troubles.

Safe Journeys,
~Jake

[Randy]

The notes below the graph have the explanations.

Column 2: Rated blower capacity (Fr) cubic feet per minute.

Column 3: Blower system output (Fo) cubic feet per minute.

[rslifkin]

Originally Posted by BlackHeron

Dreading the eventual insurance survey.

ABYC regulations should be published if they expect people to "obey" them on boats made decades before some industry group decided to make up their own "voluntary" rules and arm-twist everyone into playing their shady game.

Agreed, better access to the ABYC recommendations would be nice. And then there's figuring out the difference between ones that are worthwhile to update to versus the ones that provide a minimal benefit on an older boat, or only make sense if that system needs replacement already.

For what it's worth, my boat is only a year newer than the OP's boat, so I don't know why there's such a large difference in ventilation. Mine is an 86 model, built 11/85.

[seatotaler]

Originally Posted by Jahwork

Hello fellow Mariners,

To answer your questions, when I open the link Randy provided, it has a description of the columns directly below.

Column 1 is volume of the space to be ventilated, in this case engine room size in cubic feet

Column 2 is blower capacity rating in cubic feet per minute.

Column 3 is total system output in cubic feet per minute

Hope that helps in your troubles.

Safe Journeys,
~Jake

Thank you

[seatotaler]

Originally Posted by Randy

The notes below the graph have the explanations.

Column 2: Rated blower capacity (Fr) cubic feet per minute.

Column 3: Blower system output (Fo) cubic feet per minute.

Thank you

[seatotaler]

Originally Posted by rslifkin

Agreed, better access to the ABYC recommendations would be nice. And then there's figuring out the difference between ones that are worthwhile to update to versus the ones that provide a minimal benefit on an older boat, or only make sense if that system needs replacement already.

For what it's worth, my boat is only a year newer than the OP's boat, so I don't know why there's such a large difference in ventilation. Mine is an 86 model, built 11/85.

Well the bottom line is if you don't do the "must do recommendations" the insurance company will probably not insure the boat. Although I do have a friend who refused to make a specific recommendation regarding bonding. His arguement was given the thumbs up by the insurance company and his policy was renewed.
The other issue would be that if you refused to make the changes or upgrade and the insurance company gave you a policy anyways, and then one day the boat explodes or sinks or whatever, it would be an easy out for the insurance company, even if it seemed apparent that the cause was something different.
Given that scererio, it would be to the benefit of the insurance company to give you insurance if you refuse to comply with the recommendations. They get their yearly premiums and an easy argument to refuse a payout if something goes wrong, even if it is remotely related.

[Cpt Mark]

Originally Posted by BlackHeron

Dreading the eventual insurance survey.

ABYC regulations should be published if they expect people to "obey" them on boats made decades before some industry group decided to make up their own "voluntary" rules and arm-twist everyone into playing their shady game.

AGREED!