Engel Akuls mods

subzero · 13-06-2008

Hello fellow sub jockies..

I am currently building the Engel Akula with the optional vanes scopes etc.

I am not putting the complete build on hear as its rather straight forward.

However having said that, it would appear that from a few postings on the forum that people can have problems with getting the sealing correct of the central access plates on other Engel builds.

So I thought I would offer a solution to this problem that I have employed to this build ( which has served me well for the last 10 yrs on my old scratch built type 1X )

I replaced the 15mm long zinc plated M4 bolts with 20mm stainless steel ones as the extra length is important,( bolts , nuts, and washers about £6 from a stockists )

I did not use the alluminum plates as given in the kit but replaced these with some 1/4 inch thick LEXAN plate cut slightly bigger than the aluminium plate. ( I like to see what is going on in my boats ).

I drilled the holes into the ali plate ( plus the two extra ones ) as per the markng on the plate then I used the Ali plate as a template for the holes to be drilled into the new centralised lexan plate, tape the lexan plate onto the central deck so it cannot move and use the ali plate as a template again tape the ali to the lexan drill through the lexan and central deck,

( this ensures that all the holes are at the correct spacings. )

Where the ends of the central hole are I have drilled a third hole in the central plate at each end and threaded them all M4 as per the instructions ( you need a 3.2mm drill for the correct bore for the tap).

Use a M4 taper tap to cut the thread, when doing so only turn the tap 1/4 of a turn each time and then reverse the tap to clear the swarf about 1/2 a turn then advance a further 1/4 cut turn and keep doing so in order to cut a good thread and NOT break the tap, a little light machine oil will assist the cutting process.

The new longer stainless bolts are then screwed into place with a little locktight retaining fluid on the threads ( this stops the bolt unscrewing when being tightened should the resin later placed over the head fail )

Now to make the gaskett...clean the surface of the central deck area and the bolt threads with a good solvent ( i used cellulose thinners ) all around where the lexan plate will fit.

I then used an automotive grease to cover the entire underside of the lexan plate AND the 4 edges. ( the side that will be in contact with the central deck ) ensure that it has a good even coating this is important.

Now i used good old B+Q silicone sealant ( any brand will probably do )
form a bead of the sealant all along where the lexan plate will fit onto the central deck area between all the bolts and around them and ensure that the silicon is deep enough to come up to the exposed ends of the bolts, and a good bit around them.

Now place the lexan plate onto the bolts ( with the greased area to the silicon !! and GENTLY push down you will see the silicon start to spread out in either direction, when the bolts have come through the lexan plate enough to get a nut and washer on STOP pushing and put the rest of the nuts + washers as per the first nut.

Now leave to set for about 3-5 days...when you come back if you have put enough grease on the lid GENTLY lift off the lid leaving a perfectly flat gasket, leave again for a couple of days to fully cure, you can then remove any excess grease from the lid and silicon , you will have to slightly enlarge the holes in the lexan plate to allow for easy removal.

When fully cured you will have a gasket about 1 inch wide about 1/4 inch thick that will never harden or crack, you can even see when bolting it down when the seal is perfect as the gasket will get darker as it comes into contact with the lexan lid..( compare the photo with the nut on )

You can trim off any excess cured silicone with a SHARP craft knife to tidy it up a bit.

Much more durable and a far more reliable seal than the original

Dont forget to place some resin over the bolt heads on the underside of the deck.

Hope I have explained this well enough but hear are some pics of my gasket that should show it clearer.

Hope its of use to someone

Regards SUb.

Mankster · 13-06-2008

Great post. Sometimes 'old school' methods work best!
Just to add..
Masking around the hatch and the underside of the lid with making tape and peeling off after you have srewed down the lid will leave with with nice sharp silicon edges and no mess, without having to resort to knife.
Silicon gives of an ascetic fume which eats wires and stains brass, so do this before installing any electrics.
If after a few days you think the seal has fully cured, think again because it probably hasn't (I've pulled a few too early leaving a sticky mess).
When installing the lid prior to a dive, ensure that all the nuts are tightened by the same amount, otherwise the seal wont get compressed evenly.

Here one I made earlier