[Nick Flint Posts: 4869 Status: Offline]

Im currently doing some testing of various including Corrosion X GREASE compared to other materials and will report back here soon.

[Al Posts: 883 Status: Offline WWW]

I have found a bit of time to have a look at moving that scary air filter away from the floor, to what I consider a safer place.  It doesn't look too bad of a job to do.  I'm going to fit it above the engine cover facing front to back, so it shouldn't interfere with air entering the thrust duct. "famous last words"     I've just ordered the stainless threaded bar from toolstation which I will collect on Friday.  Another thing I shall be removing is the steel pipes they had used to connect the air filter rubber pipes.  They are starting to rust on the inside, and the only time this craft has seen water was when I gave it a test fight a couple weeks ago.  If I have to use any tubing to connect the air filter rubbers to the carb, then it will be aluminium tubing, but I don't think I need to, as it looks like one of the rubber pipes will fit.


While the engine cover was off, I had a quick look at the plug caps & HT leads, as I suspected no effort has been made to marinize them, so glue lined heat shrink has been ordered.


I haven't looked yet, but I suspect that the coils wouldn't have been coated with anything.  In the past I have sprayed the coils with PCB lacquer.  Is this still considered best practice or is there a better option?  I will unlikely have time to do anything to them until I get back from holiday as going away next week, but at least I could get what's needed ordered, so it will be waiting on my return.

[Al Posts: 883 Status: Offline WWW]

Just the camera angle 

[Ronnie L Posts: 507 Status: Offline]

Hi Al
From this angle it looks like the gas from the exhaust will hit the structure.
Constant high temp exhaust gasses really can melt anything that isn’t metal.
Just a thought

[Al Posts: 883 Status: Offline WWW]

Here's my solution to the vertical exhaust outlet.  I have seen a tractor engine get ruined with rain water entering the vertical exhaust that had no cover on the top, so this was a big concern to me especially living in the highlands where we get more than our fair share of rain.

[Ian Brooks Posts: 3552 Status: Offline]

Marlins that have visited here have been able to get over hump in 30" plus water.  Unless the plenum was full of water and the bilge pump fails  (it will, and its hard to.get when that happens). The plenum should have a number of 2" holes to allow drainage without the pump. However, you might want to check for adequate freeboard with the plenum flooded 

[Al Posts: 883 Status: Offline WWW]

This is a question mainly aimed at other Marlin owners.


I have a couple of dislikes "so far" with the Marlin 2.  First one is the position of the exhaust outlet,  On mine it exits vertically into the rear of the thrust duct.  Just seems a silly position due to the fact when the hovercraft is sat out in the rain, there is a potential for water to run down into the engine cylinders.  This is an easy fix just by bolting on a 135* stainless steel bend, which is on order.  The exhaust is remarkably quiet though, so that is a positive, just seems strange that it was left pointing vertically where it can fill with rain water



My biggest concern though is the position of the air filter, the air intake is only about an inch from the floor, it wouldn't take much rain for the water level to reach the air intake if the hover was parked slightly nose up, or even a small wave splash over the hull while flying.  I want to move the air filter, so does anyone have any ideas of how & where to place it?
 
I haven't looked yet to see how practical it would be to mount it just above the engine cover, but that's where I'm thinking it would be better placed " in the air flow and well above the floor", or the other option is alongside the duct cover, but that wouldn't look too pretty.  The reason I am so intent on moving the air filter is I mounted one that low on the freedom one I built many moons ago, and I had loads of hassle with water getting into the carb.


While I'm at it, any other upgrades I should be doing while I'm in the mood to do them?

[Al Posts: 883 Status: Offline WWW]

I took the Marlin out for it first test flight on water tonight, "not impressed"


It initially transitioned from land to water OK so I kept it in the shallows close to the shore, just in case of any issues.  I only went 100 maybe 150 metres along the shore line and thought test number 1, "getting over hump"  It failed miserably.  I started the hump test in 9" to 12" of water and not a chance, so I steered it into slightly deeper water, maybe 24" to 30", but only thing it was good at doing was giving me and itself a shower "I just got well soaked"  .

Next I found  something else that needs sorting, which I would expect to have been done at the factory when it was built "marinizing the engine electrics"  it started to misfire big time,    I thought I was going to have to jump out the craft and pull it to shore, luckily it kept running and managed to limp to dry land.  After a couple minutes on dry land, the misfire stopped and I was able to fly it back to the trailer.

The marinizing is pretty straight forward, but either I'm doing something wrong or there is a balance issue with the craft as to why I couldn't get it over the hump.

Guess I'll be chatting to other Marlin owners on my way forward to overcome this problem