SO 35 Blower

[whitebird]

New to us 2003 SO 35. In poking around in the aft section, I found a blower installed in the large ventilation hoses. I have not been able to find a switch for it and it does not seem to come on with the engine. Is it broken or is there something I do not know?

[Don Reaves]

The blower is connected to the engine's electrical system, though it doesn't come on right away. According to the wiring diagram in the owner's manual, it has a thermostatic control.

Good luck with your new White Bird,
Don

[renegade27]

Mine comes on and off without reason (as far as I can tell!). I notice it mostly after docking - I figure someone had it figured out! I thought it was fume venting, but it makes sense that it be thermostatically controlled to cool the compartment (?). Makes more sense based on its behaviour on my boat.

[Deleted]

Whitebird. I wouldn't worry about it not coming on. The blower on our 2003 SO35 didn't come on the first 2 years we had the boat. It wasn't until we took a several hour trip up river where temperatures are much warmer that it came on. The thermostat can be found in the engine compartment hanging right in front of the outlet hose.

[rick63]

The blower is controlled through the thermostat. As mentioned before it is fitted across the front of the duct just above the engine. It will only come on when the engine compartment requires cooling.

Mine normally comes on after the engine has been running for over 2 hours and then cuts in and out as required.

[parahandyonbute]

SO 33 BLOWER
Hi read with interest about the THERMOSTAT fitted to the SO 35.I have just discovered a similar blower in the ducting of my SO33.I replaced the defective 12v blower,and now when I switch on the engine ignition the blower comes on immediately.I presumed this to be correct until reading this thread,with reference to a THERMOSTAT.

Does anyone know if a 1993 SO 33 should / does have a thermostat fitted to control the engine compartment exhaust ducting 12v blower.

[mkremedy]

FYI,
I was informed by my dealer that it is now mandatory that the blower motor turn on and off in conjunction with the engine. There isn't a switch to turn it on manually and it doesn't work with a thermostat. I am not sure when this regulation went into effect, but we have a 2007 36i. At first I didn't like this, but now I don't have to rely on myself to turn the blower on or off and I also don't have to worry about the thermostat setting. I also find that the engine compartment always stays cooler.
Happy Sailing,
Martin
Remedy

[prairiechicken]

I'll revive this thread with a question about the engine blower on our new-to-us 2002 SO 43 DS.  We took her out for the first time yesterday & after about 15 minutes the blower came on & it was really quite loud.  It remained on for the duration of the hot day when ever the ignition was on.  We found the sensor & it is as described above.  Obviously we want the blower to cool the engine as required, but the blower is louder than the engine.  

Has anyone any suggestions to make that blower quieter?  We can try to add sound insulation or put rubber feet on the blower.  What have others done?

[sailbleu]

A loud blower means , either replace it , or take it out and lubricate the small bearings. I've just done the same with mine , lubricate that is. Remember , lubricating is a short therm solution , in the end replacement is the only way to go.
Those blowers tend to suffer alot because of the hot and salty air they evacuate.
Depending on the use (engine hours) they will only last for 5 years , in my case anyway. it' s not that much of an expense
I've added and extra blower in the air supply line , this way I can boost the cooling down of the engine compartment , but also , in case of total breakdown of the evacuation blower I can use it as a spare. On long trips that may come in handy. It is my believe that blowers are under estimated boatparts.

Regards

[prairiechicken]

Thanks Salibleu.  That makes sense.  The boat only has 100hours on the engine but she's been in the water all her life so perhaps the marine environment has taken it's toll.  I do like your idea of redundancy though.  It makes a lot of sense for a distance cruiser.

[sycankiz]

This is the blower for blowing fresh air into the engine compartment. It should have a thermo sensor which (on my 2003 SO35) opens the circuit at 90 degree Celsius engine compartment temperature. (Volvo MD 2030) There should be a sensor with two wires attached, one to each side, usually at the engine side mouth of the big plastic ventilation hose which blows in the air. From there it goes to a fuse just inside the engine compartment. It comes on when the ignition switch is turned on and goes off when the switch is off.

I sail down in Turkey where in summer it gets real hot and this thing starts running almost in 15-20 minutes after the engine starts running and does not stop until the engine stops.

Although the blower fan works silently (it is in fact just a mid sized fan, much like a computer fan only slightly bigger in shape), the air venting out from the starboard stern exhaust hole makes a lot of noise and can be trying. The amount of the noise it makes can be felt when you switch it of manually and feel the silence...

It came with this setup with the Volvo MD2030, but when I changed to a new engine, Volvo D1-30, the electronic starting box did not have a place to insert the blower/fan cable and as it was brand new I did not want to temper with it in any way, so I by passed the starting electronics box and attached it directly to the house batteries. Now I have to manually turn it off after anchoring and turning the engine off because it keeps working until the compartment temp goes below 90 Celsius. . I just take off one of the cable jacks on the thermo sensor and it shuts off. This can be annoying sometimes as I have to open the compartment every time i want to switch it off and do the same when starting the engine again the next time.

I am considering to run this through a switch or find a way to run it through starting electronics/ignition without too much cabling hassle.

Also the VolvoD1-30 runs at higher temperatures than the MD2030 therefore this thing keeps running more often and longer than before.

I am also told by someone that the fan blows in the air to the compartment but the out ventilation of the same is natural.(i.e. by physics/thermodynamics) However, this part I did not really get how it works so far.

[alex1949]

Hi all

Old diesel engines did not use those blowers. We actually do not need them. In cold or normal non hot areas we actually need the incoming air to be a bit warmed up.(blowers will cool it down)

I would assume that the installed  thermostat would almost prevent activation of blowers in non hot areas. Nonstop blower on is not good practice.

I am sailing in the Med. and it gets quiet hot sometimes but nevertheless I need very rarely to activate them. System has it's own ventilation through the bottom of the engine bed. I do activate blowers just to clean the diesel fumes after a long voyage before using the aft carbine.

I have a three way switch on my engine board - no blower -manually activated - auto activated through thermostat -   Usually I sail on no blower and activate it manually whenever I want to.

My 40' boat has the Volvo 55 hp (2004) and no connection to blowers was made by Volvo on the engine board.

Alex

[dbostrom]

One consideration: if your alternator is working hard, excessive warmth is not a good thing. Same deal applies to anything in your engine compartment that incorporates semiconductors or for that matter wet electrolytic capacitors (the latter not found in an alternator but ubiquitous in electronics). 

Note the familiar appearance of this product. Sure, they're selling a product but the fundamentals are correct. Some sailors go to lengths to fix the problem, the fact of the alternator cooking in a confined space.

Looking at the Jeanneau boats and seeing the little corners cut here and there in order to keep production costs low makes me think that what's left on the boat is the minimum needed, particularly in the areas of little interest to most people. If there's a blower in the engine compartment it's probably there only after a bitter struggle between engineers and bean counters. For my part, one of the things on my punch list I'm working through post-purchase is to retrofit a squirrelcage blower that will work more efficiently* against the huge back pressure of the tubing leading to the stern and as well swap out that tubing with a smooth-wall replacement. The present arrangement is horribly suboptimal from an efficiency perspective, doubtless the victim of budgeting.

*And vastly more quietly. Doing the same work more quietly comes with efficiency.

[sitara]

On my late model SO36i there was no switching at all on the blower fan. It came on with the engine and stayed on until the engine was stopped. I fitted the thermostatic switch described in hints and tips

www.jeanneau-owners.com/hintsandtips/variablefan.html and have it come on at a fairly low temperature. For short engine runs when leaving or returning to the marina the fan rarely comes on.

[dbostrom]

Ian's modification is nice indeed, as is the idea of providing some manual switching. It just struck me that the Balmar charging regulator on our boat has an output signal indicating when the alternator is working at 50% capacity; no great feat to use that as a input to blower control as well. Yet another thing to throw on the pile of to-do...

[J349er]

Jun 9, 2014 16:40:03 GMT prairiechicken said:

I'll revive this thread with a question about the engine blower on our new-to-us 2002 SO 43 DS.  We took her out for the first time yesterday & after about 15 minutes the blower came on & it was really quite loud.  It remained on for the duration of the hot day when ever the ignition was on.  We found the sensor & it is as described above.  Obviously we want the blower to cool the engine as required, but the blower is louder than the engine.  

Has anyone any suggestions to make that blower quieter?  We can try to add sound insulation or put rubber feet on the blower.  What have others done?

On my 2015 349, engine compartment blower is tied to ignition so, as soon as you turn ignition on, blowers goes on and never shuts off until ignition is turned off. And yes, it's LOUD, louder than the nifty Yanmar 20HP...

[prairiechicken]

Interesting J49er.  So the company have gone to continuous on.  I assume it is on the ignition side of the switch?  


Loud is annoying.  We're considering a squirrel cage blower but are not sure yet if we have the room to install one.

[J349er]

I think it has to do with US regulation, engine compartment fan has always to be on. Not sure how critical this is on a sailboat with a 20HP diesel. I wish I could make go on and off went ventilation is really necessary. And yes, it must be connected to ignition switch, as soon as turn on the ignition (without starting the engine) I can hear it. Woudl a squirrel cage blower move enough air? I assume they are very quiet?

[dbostrom]

Squirrelcage blowers work particularly well against high static pressure such what's produced by the sinuous, long run of internally rough tubing supplied with the Jeanneau boats. Part of the reason the existing fans howl so loudly is because they're forcing air through this tubing, causing loads of noise on the blades. Working against high static pressure is never a strong point of axial fans; the open CFM may look impressive but it plunges against any resistance.  Here's a 150ft3/min squirrelcage model from Xylem that will move more air with less noise than the siren supplied with the boat.

[J349er]

I can't tell for sure from the picture but doesn't the 349 engine blower looks like a squirrelcage type?

[dbostrom]

Yes, that's a squirrelcage. Huzzah!

Also nice to see the inlet air directly over the alternator where it'll do the most good. 

[J349er]

Good to know. It's still a fairly noisy fan though, makes more noise that the 20HP Yanmar.

[Stella Maris]

Also, let's remember that engine room ventilation is not only about temperature control. It doesn't really matter much with our low HP sailboat engines but as a rule of thumb a diesel engine needs 1/2" square of intake air per HP to be "comfortable". It is a bigger issue with the powerboat folks.

This volume is mostly catered for with the grey flex air hose that comes with our boats but because the runs are relatively long some help in moving the air along I think is a good thing. On some of the bigger boats with engines over 50 Hp like the Yanmar 4JH models, the one hose coming in is borderline.

I have condemned the relay and temp switch setup on mine so it comes on once the ignition is on. The sound of the air moving is noticeable from the helm seat but not that much of a problem in the rest of the cockpit especially with the engine running.

I take the point that I may have to change the blower motor more often than a setup that only comes on at a certain temp, but I prefer to know that my engine (one of the 100 hp 4JH models) has plenty air going into the compartment for good combustion.

[On y va]

These fans are bloody noisy yes. I have done Ian's conversion to a dial regulated thermostat too and at the same time packed the whole blower unit in very good sound proofing material I still had lying around, making sure the screws that hold the fan against the wooden panel are now also isolated, so no vibrations can pass onto the wooden panel.
All you hear now is the engine and the air escaping the scoop at the rear. What a difference!!!

[electricmonk]

I don't think the "rules" have changed since I was putting engines in boats/pumps/generator/cars/trucks/busses etc back in 1970's for Ford. Certainly then boat builders generally would leave out the engine compartment ventilation (and anything else they could leave out) claiming the engine would gulp enough air to negate them; they don't they need more air. Indeed under 15hp you can "get away with it" but in a confined space the alternator wont enjoy a long life and the engine wont perform at its best. My genny has 12hp motor with no ventilation fan but it has no air cooled alternator and everything in clam shell engine and rotor is cooled with seawater - so they "get away with it". Engines work best with cold fresh air, diesels don't have a venturi like petrol engines so they don't ice up; so with diesels as far as charge air is concerned the colder the better - in normal climates.

So over 15HP you should provide engine space ventilation and some manufacturers publish recommended CFM values, Yanmar do, CAT go one stage further and provide a fairly complex formula for the installer to fight with. Basically their formula calculates size the hoses and fans based on how much air is required to service the engine and the extractor fan. Perkins/Volvo do mention it in their installation manuals and suggest the ventilation operates all the time the engine is running. Vetus alone think diesels don't need ventilation but make and promote engine room ventilation equipment.

The blower (better described as a sucker) should be arranged to extract air hot air from the engine space with a similar or larger sized hose to allow fresh air in; so we don't rob the engine of air with the ventilation fan. The reason for this is that we don't want to pressurise the engine space, if we pressurise the engine space by supplying more air than the engine can use and out pipe can handle we risk pumping fumes into the passenger spaces, plus in essence we have unscientifically supercharged the engine both outcomes are unwanted. The only boat I know that had a pressurised engine room was the HMS Manxman, it had gas turbines. Apparently most British destroyers had pressurised engine rooms: source my Dad.

In the winter in the UK my SO43 with a 56hp yanmar the extractor did not come on. Here in Turkey on Sunday this week it was on after a couple of minutes, what a difference the ambient makes. But it would be better if the thermostatic fans we have ran on for ten minutes after the engine was switched off to extract any fumes and hot air, I agree a simple switch could do this but I would want it automatic; something less to remember.