You may ask, "Why an page on sanding tools?" or say "Sanding is
boring". Well, I found that sanding was the single most time consuming part of building the boat. I have
spent 200-300 hours (maybe more) on this project sanding. It took more time than
building the frame, coating with epoxy, laminating, fiber-glassing or installing
the engine! This is also an area
where there is a definite trade-off of tools (money) versus time. If all I had was
a hand sanding block and a small pad (1/4 sheet) sander, there could easily have been 600-1000 hours of sanding.
Since sanding is NOT my favorite part of woodworking, the added time could have
jeopardized finishing the project (and then there would have been no water skiing last year as well).
Whatever method you use, you will go through a LOT of sandpaper. Just to make
the point, for my Riviera, I used
|Hand / sanding board / 1/4 sheet sander
(whole sheets listed)
|20 sheets 36/40 grit
20 each 100, 220, 320 grit
5 each 400,600,800
3 each 1000,1200,1500
|Random orbit 5" disks (some 6" as well)
||10 each 40, 60 grit
100 sheets 80 grit
40 sheets 120 grit
25 sheets 220 grit
Also, 3 sanding pads
||6 each 40, 60 grit resin coated
15 each 80, 120 grit
|Belt sander 3x24"
||6-8 each 40, 60, 80 grit
|Belt sander 6x24" (stationary)
||6 belts 80 grit
|Disk sander 9" (stationary)
||6-10 mixed 60, 80 grit
As you can see it pays to buy the large size packages (10, 25, 50 or100
pieces) of sandpaper by the box
or roll. You save over 50% compared to small packages (5pc pack at the hardware
store) of the same product. I am
also sold on 3M, Porter Cable and to a lesser degree on Norton and Klingspor
papers. There is really no comparison to the "house brand" (Ace,
True Value, Mirka, etc.) It is most noticeable with the 36/40 grit on the sanding
board, the 3M paper is resin coated and the grit stays on. With some of the others, the granules just
fall off in 1/3 of the time! I don't know if the name brand guys make the house
brand papers, but there are sure corners being cut somewhere along the line. For
the random orbit sanders, I use stearated (white) sandpaper which does not load
up as quickly with finish or epoxy. Just be sure to wash off the piece prior to
epoxy coating or varnishing to avoid fish-eyes.
With the random orbit sander, the no-name stuff wears out quickly,
but it also has a more insidious problem. The grits are not graded as uniformly or
applied as smoothly resulting in "swirliques" (Mirka especially). These are the little
spirals that you find once you start staining or varnishing the surface. I do not think
the "Spirograph" look is appropriate for a boat or furniture. If
you get stuck with a batch of cheap sandpaper, run a fresh sheet on the cement
floor for 10-20 seconds prior to sanding the wood. This will knock off most of
the high points that make the swirls, but with somewhat shorter paper life.
Since you will be going through such quantities of sandpaper, paying 50-100%
more per sheet for hook and loop rather than PSA (Pressure Sensitive Adhesive) is silly.
Remember, when pricing out the sandpaper, boxes of hook and loop are typically
50 sheets and the PSA boxes are 100 sheets. It is better to either change back up pads
(with another grit stuck on) or simply rip off the 1 out of 10 or 20 sheets
really MUST be changed to a different grit before it is worn out. Remember, you will
destroy a couple of back up pads anyway. Buy them at the start, rather than
having to rush out to the store after one flies apart (distance record so far is
15 feet and that one hit the wall 4 feet up from the floor). Shoe Goo (for repairing running shoes) works well for fixing a
delaminated sanding pad, but takes at least 24 hours to dry.
If you think my sandpaper usage is extravagant, it is also part of the
tradeoff of time vs. money. There was an excellent article in either Fine
Woodworking or American Woodworker a few years back that compared not only
brands of sandpaper, but also the effectiveness of sanding vs. time between
paper changes. Sandpaper does not stay sharp for very long. You want to
cut the wood fibers rather than burnish them. How often have you switched pieces
of sandpaper and wonder why you had not done so 5 or 10 minutes earlier?
I have had many people ask "What kind of sander should I get?"
After reading the above section, you will see there are several parts to the
off, buy good tools. I am partial to Porter Cable and Milwaukee, but Bosch and
Makita are good as well. With the amount of stress placed on the sander(s) when
doing a project the size of the boat, it
is nice to have the tool last the duration of the project. Look back through the
Glen-L Boatbuilder Connection and the rec.boats.building newsgroup and you will see a number of complaints about
burning out sanders. With the proper tools you will have working tools at the
end of the project (for your next endeavor) rather than scrap / barely working
Sanding a boat is much different than sanding a piece of furniture. You are
sanding at full load for hours at a time rather than the much more intermittent
operation seen when doing a table or chair. The high duty cycle contributes to
burnt up motors and bearings. The higher amounts of dust and the use of silica
as a filler also contributes to greater brush and bearing wear. Better units
have bigger motor windings and bigger, sealed bearings.
I have listed the various sanding tools according to use, with most used
The best buy, as far as absolute bang for the buck, is a 5" right angle random orbit
sander (~$110-150). Do not substitute
the smaller vertical units, although you may want one as a replacement for a 1/4
sheet "Speed Block" type sander. I have a Porter Cable which has gone
through over 500 sheets of paper, and is still going strong. I also borrowed my
Dad's Bosch vertical random orbit as well as the Porter Cable vertical unit and
they just did not compare for speed of material removal. They have a smaller
orbit and quite a bit less power.
5" right angle random orbit sander
Note how paper wears off at edges first
Next is to make a long sanding board. The sanding board is nearly indispensable
(and nearly free) for fairing the frame and getting the overall
hull curvature fair. What you are after with this is large scale smoothness. The
smaller sanders simply follow the overall curves and really don't take out the
ripples. The sanding board will and its scratch pattern highlight the peaks and
the lack of scratches will show up the hollows.
My sanding board is a 4.5 x 33 x
1/4" piece of plywood scrap. It has two roughly semicircular 7"
handles on top. This board holds 3 standard half sheets of sandpaper. The paper
is held on with 3M sanding disk adhesive (or contact cement could work, too).
They are removed with the help of a heat gun and putty knife.
Sanding board top
Sanding board handle
Sanding board bottom - note 3 half-sheets
If you have a large air compressor (5HP belt drive 60 gal or more, 9+ CFM), then
you can consider air sanders. An air file is great for fairing the hull and
sanding after fiber-glassing. It works like the sanding board in that it takes
out most of the small ripples, but is powered by air rather than muscle. The air
file consumes a LOT of compressed air. My 6.5 HP compressor runs continuously
when I am sanding with it. This is a favored tool for auto body repair for the
same reasons it works well here - smoothes out the curves. This is also the
exception, where the Ace brand sandpaper worked very well.
A 6" random orbit
air sander is an inexpensive ($30-40) tool that also can remove material
quickly, but overall, I prefer my 5" electric random orbit sander (less
noisy, better speed control). Air compressors have come down in price
considerably the last few years but still expect to pay $500-1000 for a suitable
Linear air sander
Rubber sanding blocks (at least 2) 3M brand has the right amount of
"give". Having 2 gives you the ability to have 2 grits loaded. They
also seem to hide very well (I actually have 4 somewhere), resulting in me
having to go out and get another one rather than search for the one that went AWOL.
Stationary belt / disk sander. I bought a 6x48" belt + 9" disk
Delta combination unit for this project. After using it, I wish I had gotten one
years ago. It was used extensively for sanding the framing pieces prior to
assembly and coating as well as for final tweaking of the many curved, angled
and otherwise non-square joints in the boat.
This unit was ~$300 and works very
well. Belt tracking and the quick change mechanism work very well. Prices for
cheaper units may be up to ~$100 less, but you sacrifice the belt changing ease
and I wonder how well they will track after a while. If the belt does not track well, you chew
up the edge of the belt and start to destroy the sander frame. You can also
spend 2-5 times as much as well. I think this one hits the right part of the
price performance curve.
Portable a belt sander. Use a 3x24 or 4x24 (if you are really strong) unit.
The small 3x18s are too small and you will start adding ripples rather than
removing them due to the small platen and contact area on them.
The belt sander
excels at removing epoxy squeeze out on the hull. It also made cleaning up the
deck areas much easier when sanding after filling the gaps with the white epoxy
The drawbacks to belt sanders are: cost ($200-250), weight, pull (from the belt
moving) and risk of gouges. They are normally used on horizontal surfaces, but
when doing the hull you will be working on vertical areas and even with it nearly
upside down. It gets tiring very quickly, but the tradeoff is in the very high
speed of material removal.
Be careful, if you tip the sander sideways, you will
very quickly gouge out a stripe in the wood which will require filling or a lot
more sanding to even out. If I did not already own one of these, I would be hard
pressed to justify it for this project alone, but for furniture, floors, and
other projects it is great!
Belt sander - 3x24"
Most people already have a 1/4 sheet finish sander such as a Porter Cable
Speed Block. They are nice for fine finishing, but mine saw little use on this
The Porter Cable is the best of the bunch. I have used the Ryobi, Black
and Decker, Dewalt, Makita and others. This one stands out. Mine is 20 years old and
still going strong. Given the large surfaces involved, the random orbit sander
is more appropriate for the majority of the work on the boat.
1/4 sheet finishing sander (Speed Block)
Detail sanders seem like a nice idea. I have a Ryobi and it is
terrible (although the kids liked using it). It sands poorly,
the vibration makes your hand quickly go numb, the paper is very expensive (by
the square inch) and the switch failed already. I have hear good things about
the Fein, but have not used one.
Of course, you will wear a dust mask when sanding. My favorite is an old 3M
paint respirator. The charcoal in the filters is long gone, but it is
comfortable, the air inside is dust free, it seals well over my beard and also
tightly by my nose so my safety glasses don't fog up. Ordinary paper cup or
surgical style masks don't seal as well. This leads to dust in your lungs as
well as the annoying fogging problems for your safety glasses. Having a dust bag
on the sander does not alleviate this point, but does make cleanup of the
shop easier. Safety glasses are especially important with the random orbit
sander. Mine have noticeable scratches from when pieces of the paper come
flying off the edges of the disc.
If you find you are seeing "swirliques" when finishing, quickly
sand with 1 grit coarser paper than used for finish sanding while the finish is still wet. That is, if you
sanded to 220 prior to staining, sand out a small swirl with 120 grit. The paper
will quickly load up with finish and sawdust, but you can get rid of most of the
swirl if it is not extensive. Reapply the finish and continue on. Otherwise, you
will have to wait for the finish to dry and then sand it all off.
Side note on ruggedness of good tools (and momentary stupidity). When
building our house, we installed the hardwood floors ourselves. At that
time, there was only one working outlet. I was sanding the floors and my
wife was vacuuming. Having both the belt sander or the floor sander and
the vacuum on at once would blow the breaker after a few minutes. This
would mean a trip down to the basement to reset it. On about the 4th or
5th trip of the day, I reset the breaker and heard the belt sander
start and go banging against things (my new kitchen cabinets) and then
proceed bouncing and tumbling down the basement stairs. I had left the power switch
locked on. After straightening the dust bag chute, it has worked well ever