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..... because it makes a much ceaner and precision bore , has far less blow out on the other side as well .
In any case you need to go through slowly . Not meaning rpm slow (cause upper range rpm helps make a cleaner cut) , but slowly as meaning "light" pressure on the drill's forward motion . Although not necessary , it's an advantage if you can get a backer block tight up to the inside to punch into a slight amount (someone may have to hold this for you while you drill the bore .
A Forstner "shaves" away material (between it's cutting ears) more like a plane does .
Anyway , it's plastic and the more pressure and slower rpm create more heat , and the larger the dianeter of the hole the more magnified that becomes ... higher speed and less pressure makes less heat . Heat softens and melts plastics , so the less the better when boring , cutting .
FE used a Forstner ...
If you can afford it, a Forstner bit is always better than a spade bit. If you happen to have both, it's a no-brainer, use the Forstner.
For plastic, a hole saw will also work well, and better than a spade bit. It depends on the diameter, of course, hole saws don't come less than 1-1/4", I think.
For diameters less than about 3/4", you can just use regular high-speed drill bits, be sure to use new, sharp bits and work your way up to the final diameter in 1/8" increments.
with a block of wood when using high speed bits and the hole exit will be clean.
Sure you can just tie a rope to the carrying thwart, if there is one. That's usually what I do if there's not already a through-hull attachment point, and it's what I do for tie-downs on the car roof since that way there's no side-to-side movement possible between two opposing tie-downs like there is if those opposing tie-downs attach to a loop that goes through the hull (the bigger the loop, the farther the boat can move one way or the other before stopping). But attaching a rope much lower than gunwale height on the hull is better for such purposes as lining through rapids. The ideal lining attachment is a bridle which puts the point of pull directly under the hull, on the keel line, because then, no matter how sideways to the direction of pull the boat might turn when in strong current, it won't flip. Putting your attachment point a lot lower than gunwale height by means of a hole through the stem does a lot to reduce flip potential when the boat gets crosswise to the current, even if it doesn't completely eliminate it like a bridle does. All that is based on the idea that a tug-eye is even needed, which it would be if the attachment point were very low on the stem. As Pete points out below, for attaching a loop well above the waterline, simply drilling through the hull is all you need to do (no liner tube is needed).
Unless you are going to thread an end loop through a flotation tank, which Royalex canoes don't have, you can just drill your holes and run your rope or webbing through to the inside. Tie a figure-of-eight knot on each end. Or you can run a rope through both holes and tie a fisherman's knot on the hull exterior.
This is how it is done on virtually all whitewater Rx canoes and it works fine.
If you plan to use the end loops as carry handles, nylon webbing is a lot easier on the hands than rope, and works just as well to secure painters and tie downs.
Only regular drill bits need pilot holes. The angle on the blades guarantees that it is always centered in the pilot hole.
For a Forstner, spade or brad point bit, the small point on the bit is what leads it through the work. If you drill a pilot hole, then the small point has nothing to hold it in place while drilling - the bit will bounce all over, ruining the work and probably spraining/breaking your wrist into the bargain. Seriously, it really hurts.
..... generally termed "Chisle point" or "Twist drill" bits are the type of bit most people (who haven't familiarity with the array of drill bits available) , would think of when they hear the words , drill bit .
It is common practice to drill a "pilot hole" with a smaller size Chisel point bit , and then graduate with a larger (and larger again if req.) size to achieve the desired finish bore size .
This process although common practice is not required , and in truth makes no difference what so ever in the satisfactory completeion of a bored hole ... but do it that way if it makes you more confident .
Chisel point bits are not all the same . They have varying tip angles , varying chisel angles , and differing rates of flute (twist) . Different materials being drilled by Chisel point bits (because of the materials properties) , are best drilled by the proper Chisel point bit designed for the specific material ... but that gets into a more specialized aspect of boring holes , and "generally" not so important to the everyday guy/gal with a drill in their hand .
I will offer you one tip regardless the bit you decide to use ... take a center punch (pointy object) and mark a respectable dent in the exact center of where you want your bit centered . Just "tap" the center punch with a hammer to make the mark .
For what you want to do , boring a 5/8" hole through a Royalex hull , no matter which bit you decide to use ... the results will all be resonably the same if you use a "backer block" held tight up against the inside .
Time to drill your hole now , and not worry too much , it's going to be OK even if it's not perfect , it will be fine . I would use the Forstner , but it's not a mandatory requirement , they all work well enough for your needs .
The most important thing about any bit ... is that it's fresh and sharp . Boring holes with dull bits is improper practice and can leave less than desired results ... or worse !!
ps., ... I want to renage a tad on what I've said to you . You "Can" use a tiny weenie pilot hole for your operation , such as a Chisel point 1/32nd size . This will not effect how a Forstner , Brad point , or larger Chisle point works ... what it will do is allow you to know exacly where to hold the "backer block" (chunk of 2x4 , etc.) so you don't drill into the hand holding the block by mistake !! ... You understand what I just said , right ?? ... This same tiny pilot could act as your center punch as well .