Mast rake explained
After many years of debate and discussion around the best / fastest mast rake, ILCA has determined that all ILCA builders must produce boats with mast rake in the range 3808 to 3818.
The process of setting mast rake in a new boat requires accuracy and experience in the boat building process - knowing how how the resin will react as the hull and deck are joined has a significant impact on the ultimate mast rake achieved. With over 30 years experience in building Lasers / ILCA dinghies at our Fountaindale facility, PSA consistently build our boats with mast rake firmly in ILCA's target range.
Accordingly, our rake tolerances are very tight and almost all PSA boats are within 5mm of 3813 .......as they have to be as ILCA dinghies are One Design !
While you can be sure the mast rake in your new PSA ILCA dinghy is in range, we've set out step by step instructions below on how to measure your rake at home.
Before you start .........
To measure the rake in your boat you'll need:
- an ILCA 7 section (must measure 2855mm in length);
- a flexible measuring tape longer than 4 metres; and
- a marker pen.
A few tips:
- Make sure your lower section has not been sitting in the sun heating up before measuring - it will result a slightly different outcome to a 'room temperature' measurement. We've tested and proven this one !
- Always measure the rake from the outside edge of the ILCA 7 lower section (see pictures below ), this is how its done in factory and is in accordance with the ILCA Build Manual;
- Mast wear strips will change your rake. If you install one at deck level and on the bottom of the mast, mast rake will be increased by around 10 mm.
- Check your lower section is true - keep in mind that 1mm difference at deck level equates to 6.5mm on the final rake measurement; and
- Be aware that after a few hard sails, the rake in a boat can move by up to 4mm or 5 mm forward or aft.
How to measure your rake….
- Start by rigging the tape so you can measure from the outside edge of the ILCA 7 lower section - we find the easiest way is to place the tape across the top of the section so the 100mm measurement mark is on the edge (if you do this you'll need to subtract this 100mm off the final number). See the picture below:
- With your marker pen, make a small mark at the centre of the stern, 35mm aft from the starboard deck tread. This should put your mark in the middle of gunwale radius - photo below.
- Place the ILCA 7 bottom section in the mast step and pull your tape firmly. Now measure your to the point you've just marked on the radius and, if relevant, subtract the 100mm off the total. This is your mast rake. NB - You will get slightly different measurements depending on who is measuring / pulling on the tape. So just be firm, it’s not a backstay.
The photo below shows one measuring in at 3814 (after deducting the 100mm) - right on the money !
So - what are the latest go fast rakes:
For the ILCA 4 to be fast, you want as much leach tension as possible. If coaching, remember that younger kids might have trouble getting enough vang on (vang loads on an ILCA 4 are higher than an ILCA 6) so alternate strategies may be required.
3808 to 3818
ILCA 7 with new MkII sail
83kg about 3808.
90kg to 92kg – 3810, but if you're a fit hiker, creep it up to 3812.