|SJ23 Tech Tip B26, (Updated 2008-05-22) Bob Schimmel|
Anchor Roller - Dual Roller Design and Installation.
|An anchor roller is one of those really useful "toys"
to have for cruising on a SJ23, especially for all those early manufactured
hulls that were not equipped with the factory
deck anchor locker to conveniently store the "hook and line". Even if your boat is equipped
with the deck locker it still makes sense to add a roller if for no other
reason than to ease the job of retrieving 100' of slippery, slimy line
with chain. The problem with installing a one piece
anchor roller as shown in the marine catalogues, is that the factory bow
cap of an SJ23 is too soft to support one. It could collapse under
the load. However, the style of anchor roller discussed in this Tech Tip will work
on any San Juan and it's best suited for a Bruce or plough style anchor. Best of all, this design
shouldn't interfere with trailer launching but this is a judgment you will
have to make yourself as there are too many variances in trailer designs. The
installation of this roller MUST be done in conjunction with reinforcing
the toe rail and maybe moving the mooring
chocks. While you're at it, you could add a metal bow
cap or relocate your running lights. This may
sound like a lot of work but, if done together it can save a lot of time
and effort by having to the tear the bow apart only once. The bonus is that the bow area becomes water tight for
into waves, functional for anchoring and the boat should become
significantly more visible at night.
DESIGN CRITERIA - The frame work and the fasteners for this design must be extremely strong to withstand the loads of riding to the anchor during a gale force wind. Consider a typical scenario of snagging your anchor on the bottom. The first thing that most "deck apes" will do is pull the anchor line in as tight as it will go, even to the point of pulling the bow down into the water a bit. Then they walk back to the cockpit singing, "this is gonna to do it." When one of them guns the engine, the loading on the bow can instantly equal the weight of the hull. The toe rail may be strong but it's not designed to handle this type of load. This is exactly why the compression strut is so crucial and why the toe rail fasteners must be beefed up. Now just for the fun of it the frame must also be capable of holding your body weight, because at some point in time you will stand on it. However, your weight is peanuts compared to anchoring in a storm. And let's not forget the missed turn in the harbour when you jam the bow into a piling. Ouch! It would be real embarrassing to bend your brand new anchor roller, never mind the pulpit. In short, the frame must never fail, the hull should fail first. If you follow all the guidelines it will be strong enough.
Once you understand the concept of this design there are
many variations you can adopt to suite your own requirement. I know
of four variations and they all work just fine. However, as tempting as it may
seem, the one variation I don't suggest is a single roller. The anchor
line will chafe on the sides of the stem head fitting and the forestay when they are so
close. Still, if you insist on a single roller, I'm sure there's a way of
working around these problems. Let me know how you make out with your
design. I would like to hear about it.
SOME IMPORTANT CONSIDERATIONS FOR THIS DESIGN.
STRENGTHEN the TOE RAIL MOUNTING - (This is the
first job you MUST tackle as there is no point in fastening a strong
roller to a weak mounted toe rail). At the very least you MUST reinforce the toe
rail from the bow back to the forward bulkhead, then complete the
remainder at a later time. The hull to deck joint consists of two
flanges that are sealed and bolted together along the gunwale. The top of the hull flange
is sealed to the underside of the deck with a continuous bead of butyl rubber.
It is mechanically
fastened with machine screws through the toe rail and hull flanges every 6". The toe rail adds a
tremendous amount of reinforcement to this joint. The hull flange is
actually an extension of the top of the hull, turned inwards to create a
lip that the deck rests on. It is quite substantial, having a minimum thickness of 1/8".
The port and starboard hull flanges extend across the top of the transom,
bottom of the transom notch. There is no flange along the sloped
sides of the transom notch. There are no bolts through
the transom flanges. During the hull assembly a wide bead of butyl rubber is applied on top of the
hull flange and when the deck is lowered on the hull it seals the flange.
A few pop
rivets are judiciously set in place to lock the alignment of the deck to
the hull for later attaching the toe rail. Finally the toe rail is bolted on, starting at the
stern, ending at the bow.
The two toe rails are bolted with ninety two #8 size Roberts pan head machine screws (10/24 thread, 1.5" long) with 3/8" square cupped threaded nuts as shown at left. The corners of these nuts bite into the bottom of the fibreglass hull flange where they can't turn so they can be tightened by one person from above. This may save time during assembly but these small nuts concentrate the holding force on four tiny points and since there is no locking mechanism the screws will work themselves loose, creating a potential leak. If you loosen a few screws on your toe rail you will likely find dust under the heads. This dust should make you sit up and take notice, how did it in get there? Can water get in as well? To increase the overall holding power and to distribute the forces over a greater area, I replaced the cupped nuts with rectangular flat washers and nylon locking nuts. The washers were cut from (1/2 x 3/16)" aluminum flat bar as shown here. Note the relative size difference of a factory cupped nut that is on the end of the screw and my home made aluminum washers. I cut the 1/2" flat bar into 1" long sections and drilled a 7/32" hole in the center of each. Then used Sikaflex under each washer to provide uniform bedding against the uneven bottom of the hull flange and under each screw head to seal the holes in the toe rail. This is a messy job for which a helper is required. Offer copious quantities of elixir or other suitable bribe after the job is done! Whatever it takes!
To start this job I removed all cushions and cabinets and washed the settee surface as the best way to see and access the toe rail nuts is to lay on your back and look up (safety glasses). I organized the washers, nylon locking nuts and a nut driver in a parts tray that followed me as the job moved along the toe rail. I used a nut driver to hold the nut and to push up on the screw to keep the screw head up off the toe rail till the last few turns. (Alternatively you could use a tiny ratchet wrench). Ron, my helper, was outside on a ladder with the Sikaflex and #8 Roberts screw driver to twist the screws in. (Don't use an electric drill as you loose the feel for the required amount of torque to tighten the screw. Although a tiny torque wrench would be handy here). While Ron was prepared to clean up a Sikaflex spill with paper towel and acetone, he discovered that by smearing a ring of Sikaflex on the thread just below the head, his hands stayed clean, the sealant worked itself into the top of the hole and best of all, a slight amount of it oozed out under the head with the last turn. This was his sign that the screw was tight. I also didn't get any sealant down below which made my job a lot cleaner. I can't emphasize how important it is to stay clean when working with this messy goop. It saved me a tremendous amount of clean up work, not to mention acetone. The screws were tightened just to the point where the washers no longer turned. DO NOT over tighten them to the point of compressing the flange butyl rubber as this adds undue strain on the flange. (The flange butyl rubber on Panache was still pliable and looked as fresh as the day it was applied 28 years ago in 1976.). Above you can see the original cupped nuts and at right you can see my replacement aluminum washers and nylon lock nuts.
The following notes are important.
NOTE 2: Eight years after this job most of the screws had to be
retightened. One of the disadvantages of my flat washers is that
tightening the screws is now a two man job. To solve this I have
locked each nut to its washer with a dab of sealant so I only have to spin the screw to tighten the toe rail.
The screw heads were resealed with butyl rubber instead of Sikaflex. TOP
2 - REPLACE the BOW CAP - (This is an important consideration for this design) If your bow cap leaks or is beat up beyond repair, it makes sense to replace it now while the bow is open. See Tech Tip B12. for the procedure. TOP
3 MOORING CLEATS - You are going to need the mooring cleats to secure your anchor line to so verify their mounting with the bow cap off. The factory did not back up the bottom with extra pads so this is a good time to do so. Round off the corners, taper the sides of the wood and seal the wood against water absorption. Also seal the bolts holes through the deck. Finally, coat the bottom of the cleat and the under side of the screws with butyl rubber. You'll be glad you did all this in the first storm you anchor in. Sleep tight! TOP4 - REPLACE the RUNNING LIGHTS - (This is another important consideration not to be overlooked). While it's possible to make the factory deck mounted bow light more visible by raising it on a 3" tube, it makes no sense to drill a hole through a brand new water tight bow cap, metal or otherwise, for an ineffective light. Besides, the bow is already a confined area to work and you don't need a delicate protruding light to make things more difficult. A deck mounted light may meet the current collision regulations when the boat is level but the reduced visibility with an anchor or a sail lying on the foredeck is an often overlooked hazard. I also find that the glare from a deck mounted bow light reflects off adjacent hardware which reduces my night vision. It makes a lot of sense to increase your safety with lights that are out of the way and visible to others at all times. The improved visibility of the Aqua Signal Series 25 (or similar) light is night and day over the factory original. They are equipped with an 8.41MM Festoon bulb for maximum illumination.
With this style of light in mind I offer the following installation suggestions to improve your visibility:
5 - TRAILER WINCH CONSIDERATIONS - Ensure that the trailer winch AND the tree roller remain clear of the stem compression strut when launching. There are two reasons why this anchor roller design doesn't interfere during trailer launching;
In conclusion the bottom of the anchor roller stem compression strut just rubs against
the bow roller so the
strut is relatively safe from impact damage. However, the strut must be built robust enough to withstand some force against the
roller. These are two important issues
must be considered before contemplating this anchor roller for your boat. I suggest you go through a launch sequence and mark where the roller contacts the
stem. Then install the bottom fitting of the strut slightly above this mark.
could fabricate a tapered wood spacer that fits snug between the stem and the
compression strut. With concave surfaces fore and aft it should stay in
place quite nicely to support the compression strut. If you launch your boat
with a crane or travel lift then you have no concerns about the bottom location of
the stem fitting. See Tech
Tip A01 about installing a trailer bow roller. TOP
When making this
roller, keep in mind that the metal must
be bent to conform to the fibreglass, NOT the other way around. See
Tech Tip G03. While this roller looks like a simple assembly you should study the overall design details
very carefully before cutting,
drilling and assembling it. My suggestion is to work from the inside
out to the extremities, starting at the junction point just forward of the
stem head fitting. Cut off any excess metal at the ends to make a
perfect fit. It may waste a bit of material at the ends but it sure saves a
lot of frustration during construction.
RAILS - For an
SJ23 the dual roller design requires four 33" long rails to distribute the
loads over as long a section of the toe rail as possible. (While
at least 33" long bars are required to handle a 5kg
Bruce anchor on a 6" overhang, your boat may
require longer rails if your toe rails are cut short from the bow fitting. Try to
get as much overlap on your toe-rails as possible. More overlap means less
loading on the toe rail. Believe it or not, the port and starboard toe-rails are usually not the same
length on most SJ23s).
BOX BOLTS & COMPRESSION SLEEVES - A box structure, consisting of flat rails held together by threaded ready rod covered with aluminum compression sleeves around them, is very strong and light weight. Once the nuts are tightened against the compression sleeves the structure becomes extremely stiff. In the photo below you can see that I used two bolts with compression sleeves around them. This is the minimum. The compression sleeve around the forward bolt is also the bearing for the rollers. The decision to incorporate two or three box bolts is largely dependant on the length of the rails to support and fit to your anchor stock. The idea being to keep the business end of the anchor away from the hull while making the structure very rigid. Use thick walled tubing for a sleeve. Cut each sleeve so it is 1/8" longer than a roller. Use minimum 5/16" OD stainless ready rod for the box bolts through the sleeves as stainless steel bolts this long are not readily available. So cut the length of the ready rods to have about 1" of rod sticking out each side, allowing for a spacer (sleeve) to be placed between the inside rails. In the interest of being able to effect repairs in the field with simple tools, the nuts should be placed on the outside where they can be easily tightened. One technique is to use a nylock nut tightened against a half nut (double nut) at one end of the rod (or tack weld a nut to the end of the rod). Then use a single nylock nut at the opposite end. Once tightened, cut off any excess rod protruding beyond the nuts, leaving no exposed thread to snag a line. Finally cap the nuts with nylon caps or stainless cap nuts to provide protection. TOP
ROLLERS - Having two rollers is perfect for the night you need to anchor with two hooks down or to hang on a mooring with two lines. If you buy none standard rollers, it's a wise idea to buy some extras. You can never tell when the stock will run out. You could also machine your own rollers from aluminum or other hard material but that's getting anal!
If you position the forward rollers so the sides protrude beyond the forward ends of the rails they can absorb some impact if you hit something. This might just be enough to cushion against a dock to save your toe rail from crushing. A typical scenario would be when slipping bow first into a dock and not stopping in time. (i.e. using the dock to stop the boat!). On the other hand, you loose some side support on the end of a roller to handle an angled anchor line. This is a typical action when the boat starts to see saw in the wind as you pull up anchor. If you install the rollers so they protrude, leave enough metal in the rails to maintain strength and to mount the bail. TOP
BUNGEE CORD - To prevent your anchor from prematurely launching itself off the roller it is recommend to use a light line or bungee cord (shown laying loose above) hooked to the retrieving hole of the Bruce anchor. It should go without saying that you should always keep your anchor attached to the anchor line and it wouldn't hurt to firmly secure the other end of the line to the inside of the anchor locker! TOP
ADJUSTABLE BAIL - The purpose of
the bail over the roller is to keep the anchor line captive over each roller when
bouncing in four foot waves. If you fabricated the bail from 1/4"
thick stock you'll appreciate the benefits the first time you
have to anchor in rough water! It can really take the abuse from anchor or mooring lines. If the line
should slip off a roller and onto the bar stock between the roller, it
will quickly saw through, leaving you floating free with the
anchor firmly stuck in the bottom somewhere! I will add a round vertical
divider between the rollers (from the bail to the frame) to keep the anchor
line over its roller. This modification is not shown in this picture. In
the mean time I have rounded the inside of the bail to prevent chafe when the hull lies sideways
to the anchor line.
STEM COMPRESSION STRUT - The 30" long (approximate) stem compression strut (tube with flattened ends mounted between the frame and the stem) may be made to the exact length (if you are good with a measuring tape) or made telescopic with two through bolts to lock it to the final length (if you want to save time). The outer tube should be the top one to let water drain out. The bottom one should have a small drain hole just above where it is flattened. This tube also resists a substantial amount of lateral torque to add rigidity to the frame.
seen so many different techniques for installing a mooring chock that it's
beyond my keyboard pounding skills to describe how to incorporate your existing
installation with this anchor roller. If the mooring lines are run over each roller then the boat hunts
less. This is due to the attachment
point being forward of the hull which negates the need for chocks at a
final verdict is that the hull hunts
However, I still like
the ultimate strength of properly installed mooring chocks, even if they
are only a backup. I've installed my chocks as far forward as possible so
the boat rides easier at the mooring. I also
use a chock when tied to a dock.
The mounting screws for these chocks are 3.5" apart and the chock is cable
of holding 1" line or 1/2" line with a garden hose over it. There is
nothing better than rubber garden hose for chafe protection.
I installed a short length of 1" aluminum square tube under
each chock to raise the chock level with the top of the toe rail, thereby achieving a fair lead
over the edge for the line. File all
edges smooth to eliminate burrs & sharp corners. Through bolt the
square tube to the toe rail using large washers inside the angled ends of
the tube. In Panache's configuration it is
redundant to install bolts through the deck as there is no stress in this
direction and it is
difficult to seal the holes. However, it is good to fill the void between the tubing and the toe rail to
prevent "things" from growing there. Later I added a short length of aluminum
to the outside to create a larger radius corner for the mooring line so it doesn't
chafe against the mounting bolts. Make sure you install
the hooks in the
correct direction, OK! They are there to keep the line captive. TOP
HOLDING IT ALL TOGETHER
|FASTENERS - Use nylon
lock nuts to prevent the parts from coming loose.
ADHESIVE - Apply a high quality marine adhesive such as Sikkens Sikaflex, 3M 5200 or butyl rubber between the bars and the toe rail to keep water out and prevent marine growth. The adhesive will also inhibit galvanic action if you use stainless steel bars against the aluminum toe rails. See Tech tip G01.NOTES:
SELECT ANCHOR LINE BASED ON YOUR LOCAL CONDITIONS
Panache currently has 175' of 5/8" yacht braid and 25' of chain with a 5Kg Bruce anchor for ground tackle. Great security for a peaceful night at anchor.
I'm at my mooring
or day sailing
I store the anchor on a tri-angular storage shelf that rests on the
fiddles at the forward end of the V berth. This keeps it off the
cabin floor where it was a royal PIA since I stubbed my toe on
it a lot. I was quickly developing a love / hate
relationship with that chunk of steel. In 2014 I decided to do
something about that relationship with a temporary shelf to fit above the
forward berth. Then I added a 1.5' long slot from two parallel strips of wood
and fastened it on top of the shelf to receives the
stock of the 5Kg Bruce. The snug fit keeps the anchor from rolling. I thought a bungee cord
around the end of the stock would be needed to keep it there, but that is not the case. It never moves.
However, when I sleep up there I think I'll flip the anchor over to create some room for my tootsies!
I always have apprehension when a new critical component such as this anchor roller is
installed on Panache. I don't have sheltered water to move
Panache to in case of a trouble and since she looks after herself everything must work the first time, all the time! During the
first season I used this roller Panache experienced a two day 30 knot
storm, a 60 knot storm that lasted for 2 hours and a force 9 gale that lasted for about an
hour. I'm happy to report that all the new components survived
far I like this roller very much and have no problem recommending it.
The following are my observations with regard
to Panache lying at her mooring: