Custom Trailertri style opening ports

Try Flying

Many moons ago I CAD'd up an idea for converting our two fwd windows into opening hatches. I figured that I wanted to maintain the original look while allowing the possibility of great cross ventilation while at anchor even in the rain. Renders in the photo section under hatches

Well I took the first step to bring these from the virtual to the real tonight and here is my first foam core prototype

(ignore the slot/holes..that was a whoops when I flipped the part the wrong way...doh!) but this is the inside and outside profile of the hatch with the center yet to be removed and left in place while I laminate.  Hard to see but the left pic shows the rebate for the plexiglass and the right the internal baffle. A matching frame will complete the assembly and will offer water tightness thru neoprene seals and a labyrinth design which should exclude all leaks..fingers crossed.
I decided to try cheap insulation foam from Bunnings for this project as I think it will be sufficient as the strength is in the laminates and the form. 

If it works out and I'm happy with the result I may offer these for sale if there is interest but expect them to cost ~$600 for a set (TBD when I finalize the materials and amount of work involved)
Either way it will be a fun project.


Paul Spooner

That is a great idea. It is something that has been on our bucket list too, sailing in Queensland, so we might well be interested if you do decide to sell them.

Try Flying

I'm still experimenting with construction techniques (I originally was considering making a male female mold.. and still may) .  Tonight I tested just how far one can tease biax into a complex shape...

Without too much effort I could get this 400gm to drop into and out of the recesses, follow the curve and wrap around the other side... I love biax!.

I also am trialing a trick I did when making my kayak cockpit combings and used some pvc tube to lock the laminate into the narrow inner groove. It seems to be working well so will modify the foam profile to use the same trick on the outer groove. 

Tomorrow will let me see how well this has worked .. plus I did this without my glasses so might be complete shite :)

As to the rest of the design...
I'm thinking of just making the hinges a friction type so no need for a strut to hold open and two simple toggles to clamp shut. 
The fabricated sill that mounts to the cabin will have a + shape/profile with the upper leg creating the seal with the hatch frame. The side legs are what create the flange to mount to the cabin and provide a surface to engage the clamps/toggles and finally the lower leg will have a lip so one can fit a mozzie screen made of tent style material with an elastic border

As this is all experimentation at this point I'm happy to hear suggestions on any of the above or other features you think would make good additions. 


Try Flying

version 1.10 today  with the following adjustments:

  • made the two large grooves match the clear 16mm vinyl hose (I mistakenly said pvc before)
  • drilled three 6mm dowel holes in cnc bed and foam block to use dowels for location (easy to flip and still be in register)
  • added a 6mm groove to the outside perimeter to "lock" the biax in place and form the lip that will become a lap join for top side laminations

all glued up and the three vinyl tubes in place. I put some peelply over this then a flat plate of aluminium I had lying around to hold the tubes in place.  The test piece showed that one layer of 450gm biax creates a very nice stiff frame and that was with only one side completed... the full wrap will be very stiff. I mirror the code to do the port side.  Once the epoxy has gone off Ill put it back on the cnc to trim and cut the other side. Its a bit fiddly but I think its a workable method.

Try Flying

Version 1.11

I cut the frame above using the three register dowels to flip and cut the other face however I went a tad deep and touched the glass around the edges. Not a major drama but the epoxy i used for this one is Bote-coat and it remains kinda soft even when set (useful for wood boat building.. not so much this application).... so the heat from the router bit quickly turned it into goo an clogged it up. BTW never a good idea to cut epoxy with carbide tools as the hard stuff will chip them.

So on to version 1.11
Things learnt:
  • use a better suited epoxy (I didn't have much West lying around so used the ubeaut Gurit Ampreg22)
  • modify the profife to incorporate the 6mm "locking" vinyl hose on both the inside and outside profiles to creat a vertical wall for the outside laminate to lap over.
  • refine the CAM routine to speed up cutting
  • 6mm rebate slot works well to guide ocilating tool to finish the profiles and liberate the frame from the block of foam

things I may try in version 1.20 :
  • spray tack the laminate in place before applying epoxy as this step is kinda tedious and hard to get all the slippery tubes and biax to sit nice and play nice .... good thing it cold and I'm using slow hardner
    • TensorGrip makes some stuff I might trial as we have used some of there contact glues at work and they are pretty impressive.

Danny Mydlack

VERY interesting and very generous of you to keep such detailed notes - Thanks Mark!