I've been looking at the engin room ventilation arrangement on my old 33 and originally there was a series of holes in the back of the engine box with a cowel over them but these holes had been blocked off many years ago and the acoustic insulation had been applied over the top of the blocked off holes.
Basically, now there is no ventilation arrangement; the engine just sucks air in through any possible leakage path by default. Apart from being a "non solution" this reduces the opportunity for meaningful acoustic treatment.
I've noticed that the 366 appears to have engine room ventilation openings on the sides of the superstructure behind the windows.
I downloaded the perkins engine installation manual from the internet and there is a small section in there which makes sense and I managed to get further details such as combustion air volumes and turbocharger suction pressure directly from Perkins.
I'm now thinking along the lines of a pair of Fairy Huntsman type air scoops with 200 dia intake holes in the sides of the wheelhouse overhang and an acoustically treated ducted arrangement down into into the engine room.
I'd be interested to know what arrangement you guys have on your boats.
Cheers
Chas
-- Edited by chas on Friday 3rd of July 2009 02:38:21 PM
-- Edited by chas on Friday 3rd of July 2009 02:39:08 PM
at the moment because i am running a non turbo ford in my boat ,i dont need any extra air ducting because the size of the bilge the engine gets enough air.
when i find a decent 250hp engine for my boat then i will have to put air scoops on the roof with ducting down to the engine as the air in the bilge is not enough to keep a turbo engine running cool and producing the right power from the engine as they need a good supply of fresh air .
i was speaking to a marine engineer about this as his first job was with ford racing team and he said what air you pump to the engine room you must have an escape for the hot air ,it must be a consent flow so the engine gets the fresh air all the time .
Hello Chas, If i got this right i should have uploaded a photo of my little Seaward. As you can see she has the engine air intake scoops for ventilation on the sides. The engine boxes are heavily insulated, along with the inside of the hull, but the turbocharged Yanmars run suprisingly well drawing cooling air from the bilge also must help! How about a blower in engine compartment if there's room.....that would also keep the air moving. I agree with Dave P, the airflow does need to be constant....overheating is a killer of engines. Well it looks like i have just sold my boat and will be 'boatless until my harbour pilot is completed.....unless anyone wants to lend me there Lochin????....... thought not! Cheers all, Dave.
That Seaward looks very business like Dave. Your arrangement with the scoops are the lines I am now thinking along and it looks like it ties up with the recommendations in the Perking Installation Manual.
So far,Perkins have stated that for my engine the maximum air intake temperature as just over 50 deg C, the maximum negative presure at the turbo up to -125mm water gauge and the combustion air volume as 0.25 cubic metres / second and general ventilation air volume as 0.5 cubic metres / second. The last figure to me is slightly meaningless. I asked Perkins for the heat gain from the engine casing but they didn't immediately have that but I sure I could get it.
I can't see the engine heat gain being much more than about 4KW (about the same as a big domestic heating radiator) , most of the heat will go out through the exhaust. If we say that the maximum ambient temperature here in the UK is 30 deg C and we can accept a 20 deg C temperature rise into the engine air intake; that will be adequate to dissipate about 6 KW of heat so the combustion air volume should be adequate to keep the engine cool.
The problem would seem to be after the engine has stopped, a lot of heat is still stored in the engine but the ventilation has also stopped. A simple answer would be to have a hinged lid on the engine cover and just open it when you stop the engine to let the heat out.
I maybe rambling a bit here and obviously the simplest solution as far as cool running is concerned must be no engine covers at all keep it in the fresh air but bl00dy noisey. Generally sucking air from the bilges, as mine does now, means plenty of ramdom leakage paths along with the associated noise break out.
What I'm looking for is adequate ventilation for combustion and heat dissipation, minimising negative pressure in engine room and as quietly as possible.
Cheers
Chas
-- Edited by chas on Monday 6th of July 2009 10:29:56 AM
I've had plenty of time to think about engine ventilation. I first have to go back to the days of frank Nichols in Rye. I clearly can remember that one of the engineers told me that engine manufacturers would like to see that the air that is being sucked by the engine flows over the engine. This is of course to keep the engine cool. My dads boat had air intakes in the engine box. This was back in 1978. When I look at my boat which was built in 1984, they had done it totally different. As you know the enigine is partly inside the wheelhouse. In my case the air is sucked in from under the port side deck. When it comes inside the boat it is chanelled to the front of the engine so it cools the engine. This seems to work very well. when I got the boat the previous owner had modified it by blocking up the engine air intake at the main bulkhead. He had just cut some holes in the ****pit floor for engine air intake. I was surprised that the engine ran at all. I have read a lot of information about engine air intake and 99% said not to force air into the engine room (by blower). They all recommend to have a blower sucking out the hot air. Obviously the hole for the air needs to be big enough for the size of engine. The blower can be switched on during engine operation. A simple time relay will let it run for another 10 - 15 mins after the engine is switched off. I haven't yet fitted a blower as I first want to see how hot the engine compartment+ gets. It is a very simple to fit a remote temperature gauge (only about $20.00). Simon has got a lot of experience in this area.
You seem to have the same engine location as mine (1/2 in and 1/2 out of the wheelhouse)
My enquiries follow an engine fire on my boat caused not by lack of ventilation but the oil feed pipe to the turbocharger rupturing then spraying oil all over the fabric heat shield which caught fire. I managed to extinguash it very quickly and the damage seems to be limited to fairly minor things like a slightly molten air cleaner housing. The acoustic insulation in the outside section of the engine cover was both oil soaked and singed so I had to remove it and found the crazy things I mentioned in my first post. (Got to admit that I've never had a good look at the inside of my engine cover before but there again you don't tend to turn something upside down and study it closely for no reason unless it's female and pretty)
Any chance of posting some pics of your engine room ventilation arrangement?
Were you at sea when the fire happened or in port? Lucky you handled the fire so quickly. Seems you diverted a serious situation from occurring. Must have given you a fright? I haven't spent any time on my boat yet, but I will make some detailed photos of the engine ventilation asap. About the exhaust fan, you can't just take any brand because they are usually only intermittent. I think ITT Jabsco guarantee their exhaust fans for 10,000 hours.
Your Seaward looks like new!!! Doesn't look like a 5 year old boat. It is a credit to you. In my game i see a lot of 4 or 5 year old boats which look more like 10 or 15 year old boats. I can just imagine what your Lochin will be like. Did you sell the Seaward?
Good Luck,
Harold
-- Edited by Harold Timmer on Wednesday 8th of July 2009 09:46:25 AM
I was just going in to Portsmouth Harbour at the time with my missus and two friends of somewhat sensitive disposition who had never been boating in their lives.
The mussis and I were in the wheelhouse and our friends were sitting in the c0ckpit and one of them said "there is smoke coming from the engine". I knew the tide was going out so I immediately put the boat into neutral and came out on deck and said "oh dear" (except spelled differently). I killed the engine, grabbed an extinguasher then literally threw the engine cover off and emptied the extinguasher into it. The fire was still going so I emptied another and that worked. It was all over in seconds but by this time we were surrounded by police boats and harbour pilots who towed us to a pontoon.
To be honest Harold, there wasn't time to be frightened; there was only one thought in my head "my engine's on fire and I'm putting it out NOW!"
There is a fabric heat shield around the exhaust side of my turbo and another one on the exhaust elbow. I knew there was rust on the turbo casing but I'll admit that I hadn't taken the heatshield off and looked at for a while. If I had I'd have realised that the oil feed pipe was rusty too.
Apart from the ventilation aspect, this has focused my attention on the whole engine compartment including access and acoustics.
I'm sure it can't have been done by Lochin because it is complete and utter garbage. Any water on the deck can run in virtually unhindered and potentially soak the fabric heat shields which will start everything rusting.
I'm not up for grp sheathing the deck because there is equipment under there such as the fuel tank and exhaust system and I've already had to get part of the deck up to repair a leaking exhaust elbow. I know that if the deck is not sheathed I can never make it totally watertight but I can sure as hell stop water from dripping onto critical equipment again.
I'm going to try and address the whole thing and this time design it rather than throw it together giving full condideration to: ventilation, access, weatherproofing (upstands and drip channels etc) and acoustic treatment.
So, rather than reinvent wheels, let's see what everyone else has got!
Hello Harold, my little Seaward was actually nearly 6 years old but was well looked after.......and thanks for the compliments. She was a lovely boat but not big enough. Any more than three for fishing was a nightmare, but i am sad to see her go! Now i am looking for a cheap little longliner or something, to keep me going and sell on again when my Lochin arrives, but will have to wait until probably feb or march time next year before she is ready! Do you or anyone else know much about the trim blades that operate vertically instead of trim tabs? Which do you think is better? Can't make up my mind on that, although the blade type are more compact and apparently require less maintenance! Also, i was thinking of having the tinted windows like Robbie has on his harbour pilot.....they look good, i know i wouldn't get coded but i'm not worried about that, they are obviously nice when it's sunny, just wondered what theyr'e like when it's not?? Any other little 'must have's' you can recommend at this stage? Hope you are happy with your boat! Cheers, Dave.
Hi Chas, i guess a fire is everyone's worst nightmare on a boat....good job you thought and acted quickly, but thankfully i can only imagine that the need to preserve and save something you have worked hard for just come's as instinctive when put in that situation........anyway a good outcome!! Tooooo technical for me all those mathematical equations about the air volume etc, but i appreciate it needs to be worked out correctly and i believe that when engines are turned off the heat generated within actually rises for a time! I asked Harold and anyone else, about 'must have's', on a boat, tinted windows and trim blades.....any views? Now my boat has gone i have plenty of time to consider various options and accessories! My harbour pilot is underway in the mould now and i plan to get some photo's of it on here soon. Regards, Dave.
The heat generated by the engines doesn't increase as such after they are turned off (it can't, there is no longer any combustion) but they are no longer sucking air for combustion into the engine room so, without air to dissipate the heat stored in the engine casing etc; the air temperature will of, course, rise. This is why blowers are used if the engine room can't be adequately naturally ventilated.
"I asked Harold and anyone else, about 'must have's', on a boat, tinted windows and trim blades.....any views? Now my boat has gone i have plenty of time to consider various options and accessories!" --- Fire extinguashers, big ones and lots of them!!!!!!
I fitted new windscreen wipers to my boat a couple of years ago (there was only one when I bought the boat and that was knackered) with a synchroniser control and wash facility - that set up was worth having. Three wipers flapping about randomly would have driven me up the wall. They are available from B Hepworth. You should be able to find them on a search engine.
Late this afternoon I took some photos of my boat to show you how the engine vent was originally set up by the factory. Photo #1 shows the port side deck with the engine vent cover on. #2. shows the open vent (cover lying down in front) The cover still needs to be affixed. #3 shows the air channel under the dinette seat. #4. shows engine from inside wheelhouse. #5 engine shown from ****pit (without cover).
#6 shows in detail the channel where the engine box slides into (on main bulkhead) Please note rubber has not been fitted on the inside timber moulding yet. #7 Shows detail of engine box closed.
#8. Hard to explain, but shows the holes inthe engine combing where the cones slot into. This has duel purpose. 1. to stop anyone from lifting the end of the engine box (breaking in) and 2 to help align the box. #9 photo shows the underside of the engine box with the cones fitted.
#10. shows our ****pit floor. It is made up of individual plywood panels glassed over, and then flowcoated. This was how Lochin did their floors originally. (I totally agree that you need to be able to get to your equipment).
Sorry couldn't fit any more into last post. As you can see there are still a few places that need gelcoating and finishing off. Hope you understand the photos. This camera is so good that it shows up all my imperfections that I can't even see with my own eyes. Please excuse these.
Regards
Harold
-- Edited by Harold Timmer on Thursday 9th of July 2009 12:09:58 PM
Simon has got good experience with trim blades so I suggest that you give him a call. About window tinting, great during the day, but I doubt how well your vision is at night.
On our Lochin we have got a change over fuel system from Racor. If one filter is blocked, you simply pull a lever and it changes over to the second filter. Handy to have.
What brand of wiper motors are you thinking of? What about rope cutters?
Look forward to seeing your photos of the mouldings.
Thanks Harold, those photos have given me food for thought!
I notice you said that your deck is plywood panels glassed over. How thick is the glass and what do you do about the edges?
---"This camera is so good that it shows up all my imperfections that I can't even see with my own eyes."--- I wish all of my imperfections couldn't be seen with my own eyes and I also wish I had a camera that was as good as yours.
---"Please excuse these."--- Harold, please consider yourself well and truly excused!
I'll get some photos together to show what I have now.
Hello Harold, Chas and all, thanks for all the advice on equipment, a seafire automatic fire fighting system will be used along with some manual extinguishers!! Thinking i will probably go down the route of the QL plates for trim purposes. The change over fuel system you have is a good idea....might have that. Yes going to have rope cutters....too much discarded rope and net around here! Not too sure on wipers yet, but there will be three......quite fancied your idea chas, about having them linked, but then someone said to me that if you are taking spray on the port side the starboard side is usually dry so wiper blades take a battering......dunno what i'm gonna do yet! Went down to the moulders last week to see my boat coming along, Simon and the architect, Ian, were there to see her too. Things progressing well although not too much to see while still in mould, but going for another viewing soon! I should have uploaded a couple of progress photo's.....who's that bloke in front?? Cheers. Dave.
Mouldings are looking good, looking forward to seeing it out of the moulds but I suspect not half as much as you are!
Re the wipers, I said they had synchroniser control, they are not mechanically linked, the control is all electronic.
When you press the start switch they will all start as a default on medium delay intermittant wipe but you can switch any of them off and just run one or two. You also get three intermittant wipe modes (varying delays between wipes, normal speed continuous and fast, there is also a wash/wipe facility and the wiper arms can be set up on installation to park on either side of the screens.
I think the synchronisation works by starting all selected wipers on a wipe cycle together but not re-starting any wipers again untill the last one has completed its cycle. There are probably contacts in the wiper unit in the park position.
They are certianly synchronised on all three intermittant modes and normal continuous mode but I believe that on fast; they just go like bu99ery.
Check them out on B Hepworth's website.
My wiper controller is in the top left corner of the picture.
Cheers
Chas
BTW - What you can see in the picture is the control head, there is also a control box which is about the size of a book and contains the relays etc. This is mounted inside the console or somewhere else convenient. The control "box" only needs access for installation and maintenance.
-- Edited by chas on Thursday 16th of July 2009 12:56:31 PM
The hull is coming along nicely by the looks. I like those ribs, makes the boat incredibly stiff and strong. Beautiful glass work. Obviously talented tradespeople. I assume you have gone for a blue hull? Will the boat be fitted out to a high specification?
Look forward to seeing the next instalment photos.
sorry to respond so late to your question about our floor panels. I kept the edges sharp. when I glass timber panels I always grind with a grade 36 disk to get a good adhesion. There is a material called G4, which I use first as a primer. When it is still tacky you can start glassing. Make sure that the edges are saturated with resin. You can't put the glass over the sharp edges, however, if you want you can put a tissue glass on the edges. ( I didn't do that). Important though is that you do the flowcoating precisely, especially the edges, so water can't penetrate.
Hello Harold, nice to know an independant fibreglass expert thinks the moulding work looks good........very reassuring! The hull has come on a lot further now Mr.T. has reported, with the engine beds and other floor ribs glassed in. The deck is due to start around now so i need to get there to take some more photo's soon! No i didn't go for the blue, although i will probably regret it, but decided i liked the white Lochin's i had seen so went for that. She isn't going to be a particularly high spec, apart from the engines, but will have electric loo and shower, with an inverter for kettle and microwave etc. Black Kab high backed seats, air sprung with internal compressor and reclining for helm and navigator with u shaped seating arrangement in wheelhouse and a table that drops down to form a small double/large single berth opposite the galley area. Nothing too high tech or posh as i still want to do some fishing! Will post some more pics when i get some. Cheers, Dave.
Hello Chas, yes you are right i am looking really forward to seeing her out of the moulding plug.....still on target date for completion as well! I see what you mean about the wiper control....the one i saw just had them all linked together electronically but there didn't seem to be any way of controlling them independantly, yours is a good set up...i like that! Thanks for the info on site too.....very interesting. I seem to spend an awful lot of time on internet at the moment checking out various bits and pieces for the boat. Oh, by the way, as nobody offered to lend me their Lochin i have bought a secondhand 16ft.Orkney Strikeliner for a bit of fun until mine arrives.....at least i could have the title of 'smallest' boat owner on the Lochin site??? Best wishes, Dave.
Blue looks very smart, however, and I hope I don't offend anyone with a blue hull, white can always be colour matched perfectly (do it all the time) no matter how old the boat is.
Can't believe that I didn't say the thickness of the floor and the amount of glass, Sorry.
The ply used in the floor was 12mm and the glass on top of the floor is 2oz or 600grams per square metre, chopped strand matt (CSM). Roughly double that for the resin.
????....... thought not!
