help with cutting into fiberglass interior moulding?

[squarelips]

Hi you lot,

 

I am installing a stove on my grp little boat. I have decided the only sensible use of space is to cut away the moulded seating area and put the stove in there. i just want to cut away about 30cm of the bench. i would like to make as nice a job of it as possible. do you think i can just use a jig saw and buy a bunch of blades?

 

any tips for cleanly cutting into fiberglass? and then im going to have a big hole which i was just going to block back up with wood and masterboard. or is it simple enough to re - fiberglass? I am aware of how vague these questions are but any help would be great.

 

thanks for all your help everyone .

stay warm out there on the water

x

 

[kingswood]

yes you can cut with a jigsaw ,build and re fibre glass. mask area with masking tape and draw on that with felt tip pen drill some small holes enough to get the blade in then cut with jigsaw if you can get it in get right blade for the job too you might be able to use the part you cut out to re fix with a frame and refibre glass it easier to do than explain how ( ex coach builder )ps were gloves and a mask the itching will drive you mad

[The Bagdad Boatman (waits)]

Fire safety is a problem any glass fibre is a fire risk. line the area with glazed bricks or concrete, make the hole in the roof bigger and cover with stainless steel.

[Alan de Enfield]

It is surprising what structural strength 'boxes' give to a structure - I was always 'warned' by boat builders to be very, very careful when cutting away seats, cupboards etc from a GRP boat - they were designed to give support and few manufactures will put in 'extra' to allow for 'a bit being cut out'.

 

Ensure that what you cut out is replaced by something equally strong and working in the same plane.

[Arthur Brown]

Study some of the vids of The Arnold Company on youtube. OK he's using epoxy and sometimes selected carbon fibre, but there are examples of how he cuts openings in structures and makes the cut out piece into the door for the hole.

 

The only real problem is that you are unlikely to recreate the right shade of gel coat on the infil work.

[Naughty Cal]

It is surprising what structural strength 'boxes' give to a structure - I was always 'warned' by boat builders to be very, very careful when cutting away seats, cupboards etc from a GRP boat - they were designed to give support and few manufactures will put in 'extra' to allow for 'a bit being cut out'.

 

Ensure that what you cut out is replaced by something equally strong and working in the same plane.

^This^

 

Do not cut anything away unless you are absolutely sure that it is not structural.

 

If it is you will have to replace the strength.

[rusty69]

I have used an angle grinder with a thin cutting disc with success cutting GRP before.

 

If you decide against any structural modification, how about a bulkhead heater

 

Excerpt from the excellent Gougeon Brothers book on boat construction (these guys knew a thing or two about boat construction and Resin):-

 

"Using the interior to improve the vessel structure With proper planning, it’s possible to install many interior items so that they help to reinforce and support the hull skin. When bunks, shelves, cabinets, and tables are correctly bonded to a hull, they can contribute to its strength and also add stiffness to the structure by holding the hull skin in position in their immediate areas. This is especially effective if the vessel is designed from the start so that interior items are laid out to provide the most support. The interior is no longer just dead weight for the hull to carry around. Instead, it contributes to the overall integrity of the vessel. By becoming structural, interior items at least partially pay for themselves on a weight-to-strength basis."

Edited November 7, 2016 by rusty69

[W+T]

If where you cut out the box then the openings you laminate back up this will ad the strength back that has been lost. Easy to do,in the opeing where you have cut out the seat, use either plywood to block itoff or foam insulation board as in celotex type / PI board foam is cheaper and easier to work with to get a good fit, although it dosnt need to be excellent as the GRP will give all the strenght back. Then depeding on thickness lay up 450grm or 650 grm CSM with tissue on top.

 

I would get an angle grinder to cut and clean back, jig saws are a pain and hard to work wiht on GRP, a few slitting disc and flpa disc or carbide disc even better,

 

If you need more info i will help where i can to night, to tired now and off to work in a minute .

 

spell check can wait lol