The Steamboating Forum

I have seen them on other boats and my own boat "FEARLESS" came with a pair but I do not know or understand what they are. Help?

Dear wsmcycle,

They look like air inlets : on ships they were essential to bring fresh air to the lower decks and to the engine rooms , especially if the boilers were in a pressurized boiler room , to provide forced draft .
They had slightly flared cowls to trap more air and sometimes could be turned to face into the wind though this provided much less air flow than a fan in the system.

On modern ships they have long been replaced with grilled air intakes and air-conditioning systems.

On small boats and launches , particularly open ones , they are very unlikely to serve any useful purpose but some builders like to copy big-ship practice and put them on for purely cosmetic reasons.

Regards Edward.

Judging by their position near the boiler and facing forward, those may be for an increased firebox draft. Of course with a tailwind they would have the opposite effect. As Edward says, they typically serve little purpose. I picked up one from Ebay to mount on top of the engine room, it would really be ineffective and troublesome to seal off from rain etc. More trouble than it would be worth.

-Ron

This is like those stupid spinner hub caps on cars. And that means that some steam-boaters are posers? For me, this craft is all about being FUNCTIONAL and aesthetically pleasing in design. I am disappointed. I hoped my question would bring the revelation of some clever design I didn't know about.

DetroiTug wrote:Of course with a tailwind they would have the opposite effect.

-Ron

The ones I've seen (much bigger than those) were able to be rotated towards the air flow. As for rain, only driving rain should enter, as the top edge is supposed to overhang the bottom of the scoop and in port they were covered. As for effectiveness, probably next to nil. 6 knots in dead air = six knots entry draught, immediately turned through a right-angle, add any other restrictions. Result? Not a lot! On boats of our size? Definitely posie!

I suppose if turned away from the 'prevailing' they should act in reverse, and draw air.

Maybe you guys should try running on a boat that actually has them! Believe me, even at 5 knots they make a difference in the boiler room. I've run a number of similar boats with and without ventilators, and I'd have ventilators everyday. As for rain getting in, thats very rare, and minimal at the most. Of course on an open boat the are pointless.
Daniel

From the picture you post it seems that these are mounted on the passenger's shoulders, with a similarly colored harness across the man's shoulders. Perhaps an authentic Victorian era hearing aid??

I guess they are mounted on the man. Perhaps still for ventilation for the other passengers.

Ventilator cowls actually do provide a noticeable air flow below deck and are quite common on smaller yachts. There is a device, known as a "Dorade box" upon which they set, that prevents any water entering the cowl from finding its way below. There are also cowls manufactured with internal baffling that achieve the same effect. And enclosed boat can get unbearable very quickly if it doesn't have such ventilation. You'll see them on cruising sailboats a lot because in foul weather, or beating to windward with a lot of spray, the boat has to be buttoned up to keep everything below from getting soaking wet. It's just not livable below without these rather common devices. Why they are there on an open boat, however, is anybody's guess, but properly employed, they are anything but an affectation.