DIFFICULT REPAIRS MADE EASY

Type of damage:

  • holes
  • tears, rips
  • torn off brackets
  • damaged accessories
  • renewal of valves
  • bonding of accessories
  • bonding of reinforcement patches thread-air emission porous  material

Essential tools:

  • scissors or knife
  • roller
  • press-hammer
  • screw-clamp
  • pressure-weights
  • folding tool
  • brush
  • grinding tool
  • sand paper
  • cleaning rag
  • air-pump with pressure gauge
  • precision pressure gauge
  • tape measure /  ruler

Repair Material:

patches + boat skin:

  • boat material: black, red
  • none-slip covering: black

all materials and trimmings used, have been vulcanised


adhesive + thinner:

  • 1-component adhesive in tube
  • 2-component „GRABNER Workshop adhesive“: 1/8 kg, ¼ kg,  1 kg tins, mixing ratio adhesive +
  • hardener 25:1, hardener in small bottle 
  • As solvent, the original GRABNER thinner is recommended. Obtainable in 1 litre tins, or 150 ml glass bottle.

Air pressure + leak test:

Air pressure test:
inflate boot to operating pressure (0.3 bar as per operating manual). Kept  in a room of constant temperature for 24 hours. Pressure loss may under consideration of room temperature and barometric pressure be      20 %
i.e. 0.3 bar after 24 h  drop to 0.24 bar
0.2 bar after 24h drop to 0.15 bar

Air pressure check by application of soap sud.
Inflate boat to operating pressure. Cover suspect area of the air chamber with soap sud, thus localise damaged area with the help of emerging bubbles.

Air-check by immersion in water-filled container.
Since this fast and precise test requires specialised containers with electric immersion technology (as available at GRABNER), such method of examination is hardly available at the Service-Stations..

Bonding – Repair:

bonding process:

  • at a room temperature of 18-22 degree C.
  • Humidity should not exceed 70%.
  • the boat must completely be deflated of residual air.

Choice of patch size:

  • With holes, slits  and rips up to 5 cm length, patches suffice to be bonded to the outside.
  • Larger holes and slits require an additional patch on the inside.
  • Patches should be 3 – 5 cm larger than the damaged area.

Exterior bonding:

  • Select and cut suitable repair patch to suit.
  • Round the corners of the patch.
  • Place  patch on the object to be repaired and use a pencil to mark the outlines. 
  • Thoroughly roughen  the adhesive zone of patch and object.
  • Use solvent to remove dust and grease from the adhesive zones.
  • Apply adhesive to adhesive zone.
  • Allow 5 – 10 minutes to touch-dry.
  • Check: touch with finger nail, no adhesive must adhere to it.
  • Repeat process a 2nd time and allow again 5-10 minutes to touch-dry.
  • Placing of patch: Avoid trapped air and stretching.
  • Use roller tool to apply pressure.
  • Thoroughly clean off residual glue on edges, because exposed to sun, turns them brown.
  • After the cleaning process wait another ½ minute, then apply pressure again.
  • Wait at least 2 hours before re-inflating the boat. The boat best remains uninflated over night.
  • Adapt to the same procedure for bonding brackets and fixtures

Bonding from inside and outside:

  • open up slits and tears to 8 -10 cm.
  • Select and prepare  suitable patch. ENSURE: corners to be rounded.
  • Roughen the surface of the inner area all-round  3- 4 cm. The patch to undergo roughening too.
  • Use pencil to mark the centre of the patch.
  • Use solvent to clean adhesive zones.
  • Apply adhesive to the adhesive zones of the patch, and  inside the tube,(all-round 3-4 cm). Tube must not stick together.
  • After touch-drying cover patch with plastic foil.
    Place patch inside the tube in a manner that the pencil marked centre lines up properly.
  • Remove the foil.
  • Now apply pressure roller fashion.
  • hereafter apply exterior patch in the described manner.

Removing of adhesive:

Warm up with hot air blower: Heat bonding 90 degree C, cold bonding 75 degree C.
Loosen bonded joints by means of a folding tool.
Use flat pliers  to gently pull off. Warning: Do not pull off  the rubber coating of the  base webbing!
Risk of  fray threading.

Loss of air due to porosity and / or fray threading:

Loss of fray threading:
Caused by damage of interior rubber coating. Air escapes either via bonded joint, or through webbing threads (on several places too, and simultaneously), or via locations of  faulty repair.

Porousity:
due to ageing of the material. Sheathing detaches (both sides) from the carrier webbing.

Remedy to thread fraying or porosity:

Since the damaged area can not be localised, the  application by sealing compound effusion. Works only on tubes without corrugations.

Effusion-process:

  • Clean interior of tube with water.
  • Fill via the valve. Slosh water inside the tube to and fro and empty dirty water.
  • If soiled extensively, repeat process.
  • Pour LATEX Dicht-Milch compound into the air chamber.
  • Inflate boat to appr.0.15 – 0.2 bar.
  • Shake tube to slosh compound to reach all parts of the interior surfaces.
  • Drain residual Dicht-Milch compound via the valve.
  • Screw-connect flush valve with air-in and air-out pipe.
  • Depending on  circumstantial condition Dicht-Milch compound may be used up to 3 times.
  • After 5 days – 24 h conduct air check as described. If  the problem has not resolved, repeat effusion procedure.
  • Thereafter  200 – 300 ml of talcum may have to be blown into the half emptied tube, by means of a filling gun.
  • After thoroughly spreading the talcum, the tube may be deflated.

Prerequisite at service stations:

Prerequisite at service stations, is that

  • a compressed air  unit is available with oil and water separator facility,
  • Pressure reduction valve for 0.5 bar.