magnum 21

OPEN COCKPIT TRIMARANS - Revolutionary family day boats


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ASSEMBLY
As you can see from the videos here it should only take about 10 mintes to put your Magnum 21 together once you are practised at it, especially if you have a team that is used to doing it and can think ahead to the next task in the procedure.
Standing Rigging

Assembly		   
Mast steppping
Running Rigging

Jib		   
Main sail

Genoa		   
Spinnaker

For more detail on assembly of the MAGNUM 21 click on any picture below.

What follows is the method with a pre-2006 model where the floats are stowed on top of the principle hull for transport rather than alongside.

Many of the procedures shown below need only be done on the first assembly, which will take you about one and a half to two hours. Thereafter many of the items you have assembled or secured can stay as they are.

If you are keeping the boat on a mooring or berth then you only need to put the sail bag on the mainsail and furl in the jib. If you are leaving the boat in a boat park then you may need to remove the floats to reduce the width to the minimum. This takes ten minutes.

If you need to trail the boat then many items that you have tied may remain tied and all you need to do is to lower the mast and secure it and the floats. This should take about half an hour altogether.
Taking delivery. Floats unloaded - mast next. This side of the mast faces forward always. Fix the jib furler in position.
Tie the tack of the jib to the end of the forestay if it is not already attached. Fix the head of the jib to the swivelling fork Once jib is ready attach both mast shrouds before raising the mast. Usually the 3rd hole down will give the correct tension. Secure the main halyard so you can use the other end to hoist the mast into position.
With 2 people it is only necessary to attach the halyard to the tack of the jib. On your own you can use the main sheet as a block and tackle to haul the mast into position or you could use the trailer winch. If working alone then it's a good idea to attach a couple of temporary short shrouds to the float clamp eye nuts. Hinged pin used to hold the mast whilst you raise it and subsequently to hold it in position. Put the mast onto the hinged pin whilst in the horizontal position. With two people raising the mast is quick and simple.
Once the mast is secured by a halyard you can fix the forestay next. The fiddly bit! Furler ready. The aluminium cross beams are numbered to help in assembly.
The aluminium tubes that support the floats and trampolines are secured horizontally by this simple device. Before mounting the floats, first slide the front end of the trampolines on each side of the boat. Stow the trampolines off the ground whilst you fix the floats. Lift the aft end of each float into place first, because it is easier.
Next lift the front end of each float into place. If you tighten with a tool take great care that the thread does not get damaged. Click here to download a movie clip of the correct method of securing the trampolines. The quick release buckle in place.
Fitting the spray hood Adjust the tension in mast shrouds by using the main halyard and main sheet attached to the stern ring nut on each float respectively. Adjust the tension in the shrouds by using the main halyard and main sheet attached to the stern ring nut on each float respectively. Tie a figure of 8 knot in one end of the single jib sheet and thread it through the slider on the forward beam first, then through one pulley on the jib, the eye on the gunwhale and the cleat, across to other cleat, the other eye the other pulley and down to the other slider before tieing another stopper knot.
Fit boom to mast and use cunningham to tension the luff of the main sail once it is hoisted. Fix clew of the main sail to boom with double velcro. You can tie a loop in the main halyard (don't use the knot shown here as it tightens under load - better to use a Marline Spike Hitch) and turn that into a pulley for tensioning the main halyard, thus enabling you to haul the mainsail upwards with greater force. Then use the cunningham to pull the luff downwards. I prefer to use it as in the earlier picture showing the lazybag. Using the cunningham as shown here you will get a slight crease at the foot of the sail. The arrangement of the gennaker/spinnaker halyard at the mast-head is important. (This halyard is useful for raising the mast.)
Use the loose end of the very long main sheet to operate the traveller. This way the helm need only hold one rope. Spinnaker video. New 2004 gennaker furler with continuous loop Gennaker furler tensioner & arm locating pin detail


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