Getting your IRB rock fishing ready

By Scott CushmanNZ Fishing World
Getting your IRB rock fishing ready

Every rock fisher knows that the areas that get fished less usually hold better fish, the 20lb-plus snapper that straighten hooks and pull you off balance.

Sometimes the obstacle is distance and few have the calf muscles to make the journey.  Sometimes the obstacle is weather or tide and seldom do the conditions align to make access possible. 

The West Coast in particular requires little or no swell to make it safe enough to fish. But often land access is the issue because the better spots are rock ledges you can’t hike to. 

Islands are often fish magnets because the shallow zones and edges offer the kind of habitat that food sources call home. Currents that wash past these places bring nutrients and can be fish highways where large snapper, kingfish or trevally swim past. 

Identifying these locations isn’t too difficult. The issue is trying to safely land on them. Some enterprising (or possibly desperate) fisho came up with the idea of using inflatable craft to access rocky ledges as the rubber doesn’t ding or dent. 

NZLBG president Scott Bradley, like most club members, uses IRBs to get to the best ledges. Here he is a with a prime Great Barrier Island snapper.

The challenge then became avoiding punctures and so reinforcing the pontoons drove the evolution of landing on the rocks. The majority of active fishermen in the New Zealand Land Based Club (NZLBG) fish with IRBs (Inflatable Rescue Boats) that have had the pontoons reinforced with rubber armour, like sheets glued in place so that they can rub and bounce against the rough rocky platforms without being damaged. 

It’s a simple and effective idea but there are a few tricks along the way that can help save time, money and frustration. Having bought an inflatable that I intended to armour up, I caught up with Benjamin Hall, secretary of the NZLBG and picked his brains about how best to do it.

Getting started 

Before you start cutting and gluing, make sure your boat has no leaks, whether they’re obvious or slow leaks.  Repair any of these before starting. If you glue over even a tiny hole the air will escape and work its way under the armour (or second skin) causing bubbling. Once you have inflated your boat, work a section at a time. 

Typically it is easiest to work each panel of the boat as it has been constructed and use the seams as the guide for where to start and finish the sheet edges. You want to prepare the surface of both the boat rubber and the rubber sheet.

Sanding the surfaces (once cleaned) means the grip will be stronger and should be dull instead of glossy. Benjamin doesn’t recommend belt sanders (from personal experience they can quickly take you down to the fabric underlay) but instead recommends 3M varnishing pads, which fit on a drill and are easier to control while buffing and cleaning. 

Glues to use

The best glue for hypalon IRB fabric is Bostik 2403 glue, which is mixed with hardener/emulsifier. For glue supply and queries the Glue Guru company are the people to talk to ( 

If your boat is constructed of PVC, ask for the glue required for this different kind of material. Mix the two parts and serve into a dish ready for applying. Don’t mix too much at once but rather enough for each section you are working on. 

When you are working a panel of rubber on to the boat, the main challenge is trying to place the panel in exactly the right place as once the two surfaces touch, they aren’t coming off without a fight. Smearing both surfaces and then applying when tack dry creates a suction like bond so it has to be perfect the first time you put it in place. 

New Zealand Land Based Club secretary Benjamin Hall about to re-glue his Inflatable Rescue Boat (IRB) for landing on
the rocks.

Little tricks

There are a few tricks though that can help you avoid disaster. Benjamin recommends starting at the top of a panel, and working a 5-10cm strip across the whole upper edge (about a brush width). Don’t do more than this. 

Glue and carefully place the top strip of rubber where it should be. An extra pair of hands can be very helpful at this point to ensure it doesn’t accidentally touch the wrong part. 

Once it is in place and stuck fast, you can then work on gluing the next section and then laying down the sheet further until the whole sheet has been glued into place. 

Once the full section has been glued in place, use the razor to carefully cut any overlap and make the edges fit properly.  

It is better to glue a larger than required panel and then cut to exact parameters. Do this slowly as it is very easy to puncture the inflatable skin underneath and tearing off a freshly glued panel to repair the razor cut is a lot of hard work. 

Another tip here is to cut or score 90 per cent way through the rubber sheet that has been glued in place and you should be able to tear the rubber cleanly away from there. 

Cutting a straight line is made easier when a length of masking tape (15-20cm long) is stuck into place first and then used to guide the final cut.

The 3.8m Arancia IRBs are perfect for this kind of activity because they are built for safely negotiating scary waves and hair-raising swell. Surf clubs will sell their boats from time to time and talking to a club about the turnover of their stock can be a good move to plan in your purchase. Trademe is the alternative and cheaper deals are found in winter, which coincides with a good time of year to do the ‘armouring’ of your boat.Rigid inflatable boats (RIBs) are also worth looking at.

The right rubber

The rubber sheets best for the job are insertion grade rubber. Rubber with nylon inserted into the sheet helps it keep its shape and makes it less likely to tear on rock, instead bouncing’ off those hard surfaces. Some types of insertion grade rubber have cotton inserted for strength but nylon insertion is a more durable product and won’t rot. Thorndon rubber ( are good suppliers of insertion grade rubber sheets. 

Three-millimetre rubber is a good starting thickness for the sections that will take the punishment and 1.5mm can be used for the areas that get less contact as the mix of different thicknesses will keep the overall weight down. 

Once the rubber sheets are in place, fill in the gaps between sections with a rubber sealant. The gaps will hopefully be only a few millimetres apart (if your cutting has been done with a steady hand). A good sealant to use is Quilosa Sintex MS-35 plus, again from the Glue Guru. 

The trickiest parts to glue the sheets on to are the curving sections (usually the nose). Gluing sheets on to the top (and not just the bottom/sides) can be good to guard against wear from stepping on and off when getting on to the rocks (again on the nose). 

Doing the same for the sides can help guard against the spines and hooks that can come into contact with the hypalon from fishing out of the boat itself.  If you have handles that are placed in such a way that they flick lots of water up during travelling, a heat gun is useful for removal.

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