Buyer’s Guide – J/105 Class Association

J/105 Apparel

By J/Boats

J/Boats is pleased to host the following
links for apparel embroidered with the J/ trademark. These companies are licensed
by J/Boats, Inc. to provide regatta T’s, shirts, caps, jackets and a full range
of apparel. Please visit these sites for the latest on selection, pricing and
order information.
U.S.: VSport
UK: J/GEAR – EUROPE

Sources for Half-Hull Models

By Nelson Weiderman

I know of four sources where half-hull
models can be purchased. They run from $300 to $500. Let me know if there
are additional sources that should be listed here.

1. Trident Studios (Andrew Burton)
in Newport, RI. Tel:401-846-9505.
E-mail: andrew@tridentstudio.com .
Website: www.tridentstudio.com.

2. The Scale Model Company, Menominee, MI. Tel: 715-582-5074
E-mail: mmc@cybrzn.com.

3. Milton Thrasher, Sarasota, FL. Tel: 941-966-9172.
E-mail: mthrasher@verizon.net ,
Website: www.angelfire.com/fl4/mft

4. Zuma Boat, Inc (Mas Azuma), Atlanta, GA Tel: 404-272-7889.
E-mail: info@halfhull.net,
Website: www.halfhull.net

Note: Jeff J reports that the late
Tom Harsh, who founded the original Scale Model Company, sold his plugs (all
the J models) to Andrew Burton. The new Scale Model Company is under different
management and may not yet have a track record. They do, however, show photos
of several J/105 models on their website. Please send me feedback.

Table and Cooler Mods

By Per Boeymo

A J/105 table that doesn’t shake and igloo cooler mods are posted on the Lovise�website.

Heating and Galley Mods

By Per Boeymo

Interesting heating and galley mods are posted on the Lovise website.

Wheel vs. Tiller

By Stuart Burnett

I have hull # 198 with a wheel. There
is another J/105 at my club with a tiller. I’ve not sailed with the tiller, but
the other owner has steered my boat. Here are the trade-offs I’m aware of…

TILLER PROS:

Better feel upwind in light air.
In my experience, my boat (with wheel) goes very mushy in under 6 kts true
wind with the class sails, though this may be true for the tiller boats too.
My impression is that the tiller is a little better in these conditions. These
are the only conditions when I think the tiller has an advantage.
Allows helmsman to sit about 12″
further forward. While most of us drive upwind from in front of the wheel,
basically opposite the pedestal, with the tiller you can easily get forward
to the back of the traveler. Some helmsman even sit in front of the traveler
with the tiller.
Immediate feedback as to rudder
angle. The tiller is an absolute indicator of current rudder angle.
More cockpit space at the dock
with the tiller folded up.
Tillers are mechanically simpler
and inherently more reliable.

TILLER CONS:
- Obstructs the helmsman’s ability
  to change sides of the boat. The cockpit is too deep to work well with a tiller
  and the tiller comes forward to within 12-15″ of the traveler. You either
  have to lift it and go under on tacks, or try to straddle it (and its very
  high compared to the cockpit floor) and go over. I know at least one owner
  who claims to have hit a boat during a race because his attention was distracting
  trying to maneuver around the tiller.
Steering downwind in waves is
tough. A tiller works best when the load is a constant pull, like the weather
helm generated when sailing upwind. When the loads are reversing (i.e. pull
then push) when the boat is steered downwind in waves, the tiller and cockpit
don’t work as well.
The cockpit is not well configured
for a tiller. You can sit on the cockpit seat behind the traveler and hold
the tiller, but then you’re sitting low behind the cabin trunk with limited
visibility. Without the pedestal for the wheel, there’s no good place for
a magnetic compass, or to brace your feet upwind to keep from sliding into
the boat if you sit behind the end of the cockpit seat. Some owners have added
teak strips to the inside edge of the after cockpit seats to provide a foot
brace.
Auto pilot choices are limited
to slow “tiller pilot” devices which are hard to setup and engage or an under-deck
autopilot.

WHEEL PROS:
- The wheel is the configuration
  recommended by Jeff Johnstone. (Need we say more?)
The wheel fits the configuration
of the boat better. With the helmsman’s cushions installed, the boat is incredibly
comfortable to drive whether racing or cruising. There are many different
driving positions that work with a wheel. There is only one driving position
that works with the tiller.
The helmsman’s ability to change
sides of the boat is enhanced. Its easy to duck to leeward behind the wheel
to watch a crossing or mark rounding. Also driving from directly behind the
wheel downwind seems more natural to me and allows me to move around for a
better view ahead.
The pedestal provides a foot brace
for the helmsman as well as a place to mount the compass, other equipment,
and gear holders (i.e. winch handles, binoculars, handheld VHF, instrument
& autopilot remotes, drink holders, etc.)
When cruising as you can lounge
across the entire rear deck which is not interrupted by a tiller, or against
the rear lifelines and drive with your feet.
The wheel is very responsive in
all conditions except very light air. Upwind, I rarely move the wheel more
than .25 meters. Also the mechanical advantage of the wheel keeps the helmsman
from tiring as quickly in heavy air and the padded elk-hide covering is very
comfortable and sure-grip.
The wheel controls the boat better
when backing up, without the tendency to slam to one side that a tiller has.
Even without an autopilot, the
wheel’s built in brake serves as a “poor man’s autopilot” and allows you to
dampen the sometimes too sensitive steering of the boat.
Above-deck wheel autopilots are
generally more convenient than tiller autopilots. The wheel autopilot is always
“ready to go” by just flipping the tensioning lever. The tiller autopilot
has to be run in and out to match the tiller position, snapped on to the pin
in the tiller, then “engaged”.
The wheel is more natural for
non-sailors who have never used a tiller.
The wheel is just plain sexy.
WHEEL CONS:
- The wheel costs $4500.
- The wheel takes up more room in
  the cockpit, particularly at the dock.
The wheel may be less sensitive
than the tiller upwind in light air.
Depending on the helmsman’s arm
length, the helmsman may not be able to lean fully back against the lifelines
and reach the wheel.
The only above-deck auto pilot
that works with the Edson Diamond pedestal is the Autohelm 4000 ST. This does
result in a very clean installation, however.Stuart Burnett

srburnett@rmc.com

J/105 “LEGACY”

J/105 Trailer

Triad Trailers

A number of J/105 owners have purchased
trailers from Triad Trailers Ltd. in Danbury CT. They have various options. For
the J/105, the keel rides 6 inches off the ground. An optional keel box is enclosed
on the front and the two sides. Among the options for the J/105 are 6,000 pound
tandem axles with hydraulic or electric brakes (electric brakes are recommended),
lift-off or float-off package, bow stop and ladder (included in float-off package),
mounted spare tire, and two rear stabilizing jacks for ability to change the spare
tire.

Triad Trailers, Ltd
90 Danbury Road
New Milford, CT 06776
Tel: 860-354-1146
FAX: 860-350-2550
email: triad@sailnet.com
website: www.sailnet.com/triad/

J/105 Interior Options

By Stuart Burnett

There are two basic interior options,
the “Traditional” now called the “Optional” and the “Euro”
now called the “Standard”. I will refer to them by the more widely know
names, “traditional” and “Euro”.

The traditional interior has the
settees forward against the main bulkhead, and the galley & nav areas aft.
The traditional interior has NO INTERIOR ACCESS to the areas of the boat aft
of the companionway bulkhead.

The Euro interior has the galley
and nav areas forward next to the bulkhead and the settees aft. The Euro interior
has large (approximately 3 x 2 feet) openings through the companionway bulkhead
into the “cockpit lockers”. Zippered-mesh openings are provided to
separate these areas from the main cabin.

Most of the advantages and disadvantages
of either configuration center around the fact that the aft 12-18 inches of
the main cabin is tucked under the cockpit. You can see this if you look closely
at the interior diagrams in the brochures. Also, remember that there is no standing
headroom anywhere in the boat. With the companionway slide pushed forward, you
can stand upright under the dodger in the back half of the cabin.

I should tell you that I’ve ordered
a J/105 with the Euro interior, so keep that in mind while your reading this.
I’ll explain why at the end. Here are the advantages and disadvantages of each,
as I see them.

TRADITIONAL INTERIOR ADVANTAGES:
- The settees more accessible. You
  can recline in the settees with a pillow against the forward bulkhead and
  use the bulkhead mounted reading lamp.
The table location is all the
way forward to the bulkhead, out of the way of the companionway. This gives
you room for four at the table.
The nav station is aft, near the
cockpit. If you install electronics (GPS, radar, etc) on pivoting arms adjacent
to the companionway, you can swivel them out to see while driving, or in to
work at the nav station. You can do this with the Euro arrangement, but the
nav station will be forward, not near the GPS.
The nav station and galley are
closer to the electrical system, simplifying wiring and panel installation.
(But TPI does this anyway…)
You can stand upright in the main
hatch area while “cooking”.
The smells of sails, anchor &
rode, fenders, and other wet gear stored in the cockpit lockers is effectively
isolated from the cabin. Engine smells may also be isolated, although the
front of the engine compartment is still in the main cabin, as is the fuel
tank (under the port settee). On the other hand, several owners I’ve talked
to have installed vents through the bulkhead to try to improve ventilation
and drying in the cockpit locker.
There is more storage space in
the cockpit lockers.

TRADITIONAL INTERIOR DISADVANTAGES:
- If you take rain or spray down
  the companionway, it goes onto the galley and nav station equipment. Several
  owners have mentioned this as a problem.
There is no room for chart storage
in the top of the nav station because the cockpit restricts the ability to
lift the top up.
You can’t remove the cooler without
removing the companionway ladder and swinging it out of the way.
The locker doors to the nav station
and galley can’t be fully opened without removing the cooler.
There is no interior access to
the boat behind the companionway. A rather large area of the boat is only
accessible through the cockpit lockers. ACCESSIBLE “Internal storage”
in the traditional interior is limited to the hanging locker in the head,
the area under the v-berth, and the areas behind the settees.
If you close the engine seawater
seacock when you leave the boat, you must climb down into the port cockpit
locker to reach it. It cannot be reached by normal people just leaning into
the locker.
This is now the “optional
interior arrangement” offered by J/Boats.

EURO INTERIOR ADVANTAGES:
- The Euro interior has two large
  openings into the cockpit locker area. At a minimum, this greatly expands
  the area of the boat that is accessible for storage from inside the cabin.
Optionally, one or two quarter
berths can be added in the sail locker area. These berths become extensions
of the cabin settees. They are about 40″ wide at the head and over 6.5′
long. They form good seaberths, small doubles for an additional couple, or
good interior storage areas.
The boat looks a little more “Yachty”
because you see the galley and nav areas when you come down the companionway,
instead of just the two settees.
Foot room is restricted for the
part of the settee that is located under the cockpit, however the cooler forms
a very comfortable “ottoman”.
The cooler can be removed by lifting
it onto one of the settees without removing the companionway ladder.
Access to the nav station and
galley is improved, because they are not tucked under the cockpit.
The nav station top opens for
chart storage.
The locker doors under the nav
station and galley can be opened (without having to remove the cooler).
By opening the port mesh curtain,
you can easily reach the engine seawater seacock from the port settee.
Ventilation to the cockpit lockers
is greatly improved.
This is now the “standard
interior arrangement” recommended by J/Boats.

EURO INTERIOR DISADVANTAGES:
- The cabin table is moved slightly
  aft and the table is smaller. The table interferes somewhat with companionway
  access unless the back is swiveled slightly to port.
The nav station is not located
adjacent to the cockpit so it is difficult to locate electronics both “at
the nav station” and viewable from the cockpit. Also, electrical runs
to the nav station are longer.
The settees are partially under
the cockpit and somewhat less accessible.
Neither end of the settees are
adjacent to bulkheads (the aft bulkhead being cut away for cockpit locker
access). If you try to recline with your head against the nav station and
galley, there are no nearby lights for reading.
Headroom near the nav station
and galley is less since you do not have the ability to stand in the companionway
and be very close to them.
The smells of sails, anchor &
rode, fenders, and other wet gear stored in the cockpit lockers is not as
effectively isolated from the main cabin.
There is less storage space in
the cockpit lockers.

MY EVALUATION

With all these trade-offs considered,
I elected to order the Euro interior with a single starboard quarterberth. The
main consideration here was wanting the QB. My current boat is a Beneteau 305.
I really felt the QB helped bridge the difference in interior volume, accommodations,
and storage between the 305 and the standard 105. I really like the additional
accommodation options offered by having the QB. I have a 10 year old daughter
who will be happy to sleep there, leaving the middle of the boat free for “living”.
Also the quarterberth gives you one good seaberth, though lee-cloths can be rigged
for the settees if you get the optional SS interior handrails.

When you add the QB, JBoats offers
the option of putting a bottom on the cockpit locker to make a shallow (2″)
locker, or leaving the original opening into the QB. I’m getting the shallow
locker, which I intend to set up for my “above deck” navigation. The
single port cockpit locker is more than enough for what I want to be carrying
on the boat.

I was concerned about the decrease
usability of the cabin table, but most owners I’ve talked to don’t set up the
table down below anyway. They only use it in the cockpit if they have it on
the boat at all.

We don’t cook much on the boat and
I tend to navigate from the cockpit, so having the nav station and galley aft
were not important to me. On the other hand, being able to remove the cooler
without removing the companionway ladder I consider to be a big plus.

Finally, I do like the “look”
down below of the Euro interior better. With some pictures and nautical do-dads
on the front bulkhead, you can almost convince people they’re on a yacht, not
a very expensive daysailer.

Hope this helps you as you look
at the J/105. Its a great sailing boat with a very strong designer, builder,
and class organization supporting it. The boats are holding there value well
due to the demand for them as one design racers. If you spend most of your time
sailing rather than anchoring or at the dock, its great.

Stuart Burnett

srburnett@rmc.com

J/105 “LEGACY”

J/105 versus J/35

By Stuart Burnett

In comparing a “traditional offshore
one-design” racing boat (particularly a used J/35) to the J/105 it can help
to consider the following questions….

Do you currently own a boat and
have a crew? If not, how many sailing buddies do you have lined up for your
new boat? Do you prefer wheel or tiller steering? Would you enjoy a big “sit-in”
cockpit while daysailing, or are you comfortable with having people sit on the
deck? Do you like buying a big sail inventory and the challenge of choosing
the right sail for the conditions? When you’re daysailing do you sail short-handed?
Would you use your boat more if you could singlehand it, or if two people could
sail it at 90% of its efficiency, or if you had a dodger to get out of the weather?
Do you like having checkstays? Would you prefer a hull that’s laid-up as a single
primary-bond unit with integral structural grid, rather than layer upon layer
being hand laid and secondary bonds to the internal structural elements? Do
you require or prefer shallow draft? Do you prefer a light weight boat with
a high ballast to weight ratio? These are some of the questions you should be
asking yourself.

After considering these same questions,
I’ve just ordered a J/105. Here are some of the reasons.

For me the number of people I have
to get together to race has, over the years, been a big deterrent to my getting
my boat (formerly a Beneteau 305) out on the course. That’s why I’ve ordered
a J/105. Competitive J/35s are racing with 8-10 people. Furthermore, the J/35
class has a maximum crew weight of 1650 lbs. vs. the J/105 class maximum of
970 lbs. Basically that’s ten 160 lbs. for the J/35 or 6 for the J/105. BTW,
you can race the J/105 effectively with 5 people, though with PHRF sails some
owners do prefer 6.

I believe there was a wheel option
for the J/35, but I’ve never seen one. The J/105 was the first J/Boat to offer
the Edson Diamond Series aluminum wheel with the lightweight custom molded GRP
pedestal as an option. Much of the fleet has been equipped with this 48″
wheel which allows you to steer upwind while sitting in a “tiller”
position, with your back against the windward lifelines. The wheel is, arguably,
as sensitive upwind as a tiller and much easier to handle downwind in waves
when the tiller tends to throw the helmsman around. It’s also better at the
start and in close quarters maneuvering where the ability of the helmsman to
move quickly from side to side makes maneuvering easier. Another advantage of
the wheel setup on the J/105 is that the GRP pedestal allows an Autohelm 4000
Wheel Autopilot to be mounted internally with only the wheel ring visible.

My family likes the security of
a “sit-in” cockpit. The J/105 has 6.5′ of cockpit seats. I’m guessing
the J/35 has 3′. Also the J/105 has a small coaming to divert water down the
side deck instead of having it wash over the cockpit. The helmsman’s areas are
similar except the J/105 has the coaming to help keep you up on the deck. There
is a note on the J/Boats J/35 web page that the J/35 has a new “single
level cockpit with raised 2″ coaming to deflect water aft”, but I
don’t know how many have been built with this option.

As for headsail inventory, for J/105
class only allows a 100% jib and one 77 square meter asymmetric spinnaker. For
PHRF sailing most J/105 owners add a 155% light/medium genoa and a 110 square
meter asymmetric spinnaker (the largest A-sail allowed under PHRF for the J/105
rig dimensions). Some PHRF areas are now giving the J/105 a credit for racing
with only the one-design sails, so owners have a choice to buy the two extra
sails or not. The J/35 class allows four jibs (two genoas, a working jib, and
a storm jib) and 2 spinnakers for class racing. I don’t know how many jibs and
spinnakers a “well equipped” J/35 carries for PHRF racing, but just
for the jibs I would image there are light and heavy #1s, a #2, a #3, and a
storm jib.

Many J/105 owners sail the boat
shorthanded or single-handed. Remember that the standard sail is a 100% jib
on a furler. Most owners also get their PHRF 155% genoas cut to fit the roller
furler since it eliminates so much crew work. At the dock I’ll cover my jibs
with a zippered sock raised on the spinnaker halyard, so the racing sails have
no sacrificial UV layer to degrade their performance. When we go daysailing,
there’s no sails to bring up on deck, and there’s no pile of four or five jibs
and spinnakers down below. Of course you could add a roller furler to the J/35,
and get some cruising sails cut to fit it, and put the furler and the sail on
every time you want to go daysailing, and take the furler and the sail off every
time you want to go racing, etc. I’m sure some J/35 somewhere has been equipped
with a dodger for cruising, but every J/105 comes with a dodger and it is required
to be installed for class racing.

As for the spinnaker, the A-sail
can be loaded in a spinnaker sock to make even single-handed spinnaker sailing
possible, with the addition of an above-deck autopilot. The hardware to control
the sock, but not the sock itself, comes standard on the boat and is class required.
For racing the A-sails are generally thrown and retrieved out of the front hatch
with all lines attached and never removed (except to change sails). A retrieving
line attached to the tack of the A-sail allows a windward douse which collapses
the sail as it is pulled around the jib and down the hatch.

I don’t have any opinion on the
check stays issue except that the J/35 has them and the J/105 doesn’t. I’m assuming
here that the J/35 doesn’t require them to keep the stick in the boat. When
I’m racing the additional level of control of the upper mast would be nice.
When I’m daysailing, they’d be a pain. You probably make your decision on the
boat based on other issues then convince yourself that having them or not is
what you wanted anyway. I’m just as glad to not have to carry the extra crew
to work them.

The hull molding question is a little
bit unfair. All J/105s have been vacuum bagged. Hulls after 155 are SCRIMPed,
which is TPIs process of laying up dry glass and core material, then introducing
all the catalyzed resin at once so that the entire hull is molded as a single
primary bond with no voids due to the vacuum. Basically you’ll only get this
on a new J/105. On the other hand, I don’t think they’re making new J/35s, so
at least you have a choice.

The deep draft of the J/35 is 6.9′.
I’m not sure if any shoal draft boats were built. The deep draft for the J/105
is 6.6′, and a shoal draft option of 5.5′ is available. The boats are designed
so the righting moment of both configurations is the same, although the deep
draft enjoys and advantage upwind in light air. In class sponsored one-design
racing, the shoal draft races with a 3 sec/mile rating credit. Most fleets have
standardized on the deep keel, while the Chesapeake Bay Fleet has gone shoal
draft, as are many of the Florida owners. About 80% of the boats that have been
built are deep draft.

According to the numbers published
on the J/Boats web site, the J/35 displaces 10,500 lbs. with 4,400 lbs. of ballast
for an excellent ballast/displacement ratio of 42%. The J/105 displaces 7,750
lbs. with 3,400 lbs. of ballast for a ballast/displacement ratio of 44%! The
J/105 has a D/L ratio of 134 vs. the J/35’s 174. The SA/D ratio also is in favor
of the J/105 at 24 Vs the J/35’s 21. This is even more of an advantage when
you consider the ease of use of the J/105s sails with the standard roller furler
and A-sail. Also this probably understates the A-sail’s size advantage over
a traditional spinnaker. So the J/105 is lighter for its length, has more sail
area for its weight, and has more ballast for its weight. Taken together this
is probably the difference in a boat that will plane on a reach, and a boat
that will only surf downwind. However, the J/35 will sail dead downwind, probably
at a higher VMG and with somewhat more excitement in a blow.

The J/35 does rate faster than the
J/105 under PHRF. Rod Johnstone suggests that a PHRF equipped J/105 is six secs/mile
slower than the J/35 on the standard windward-leeward courses that are so prevalent
today. On an Olympic course with some reaching the suggested rating difference
falls to 3 secs/mile. Remembering that the “base” rating of a “0”
boat is 600 secs/mile, so a 6 secs/mile rating difference represents a speed
difference of 0.9%. J/105s with PHRF sails and deep drafts rate from 71 to 84
depending on the location.

The J/35 does have an advantage
in having more head room and more interior accommodations, including a real
ice box, an optional oven, a shower, and two quarterberths. The J/105 uses a
removable Igloo cooler under the companionway steps, has no oven, and quarterberths
are optional. On the other hand, the J/105 table and settee backrests are made
to fit in the cockpit, where more people spend their time. Of course the J/35
needs the two QBs to stow those six headsails anyway. Also you’ll need the bunks
for those 10 crew members. (When will someone design a boat that can be effectively
raced with only the number of people for whom there are bunks?) The galley and
nav station areas are similar on the two boats, although the J/35 gets the nod
for having more head room in those areas.

I’d recommend you go to the J/Boats
web site at http://www.jboats.com and look
at the information on both J/Boats’ pages and the class associations’ pages.
In particular you should read over the J/35 class rules (23 pages) vs. the J/105
class rules (2 pages). You can see the effect the “pros” had on the
J/35 class in the ’80s. The J/35 class has had to specify everything you can
and cannot do to the boat. The J/105 class rules benefited from J/Boats experience
with the J/35 and J/24 classes. They basically say, “You can’t change the
boat unless these rules specifically allow it, period, the end.”

The J/35 has been the premier offshore
one-design fleet in the US if not the world. I believe approximately 360 boats
have been made since its introduction in 1983 or approximately 25 hulls per
year. The J/105 has sold 198 boats since 1992 or 40 hulls per year. Some people
will never be comfortable with the J/105’s style of sailing, the small jib,
or the A-sail. For them the J/105 will never be a replacement for the J/35.
For the rest of us who just want close racing in large boats without hassles,
the J/105 may be the next premier offshore one-design.

I hope this biased view was helpful
in outlining some of the issues and tradeoffs between these two great boats.
Really, the J/35 is a great boat as are most of the J/Boat designs. I’m just
suggesting you also look at their latest successes…

Stuart Burnett

srburnett@rmc.com

J/105 “LEGACY”

Hand Layup, Vacuum Bagging &
SCRIMP�

By Stuart Burnett

I’m not an engineer, but this is my
understanding of the difference between hand lay-up, vacuum bagging, and SCRIMP�.

In both hand lay-up and vacuum bagging
the initial process is the same. The fiberglass is laid up and wetted out by
hand. That is, gel coat and other “liquid” layers are sprayed into
the mold and allowed to cure until tacky then layers of laminate (fiberglass
cloth of different types) are hand “wetted” or saturated with resin
which already has catalyst in it and laid into the mold. The cloth is smoothed
with squeegees, and more resin is added until the cloth appears to be completely
and thoroughly wet through with resin. Any dry spots result in voids which can
blister and provide no adhesion between the laminate layers. This process continues
layer after layer, until the entire “outer” hull is finished. As long
as the underlying layer of laminate is not completely cured, a PRIMARY BOND
is created with the next laminate layer. That is, their resins “co-mingle”
and harden as a single structure. I do not know if this can all be done in one
day. If at anytime the construction process stops long enough for the previous
laminate layer to completely cure, then a SECONDARY BOND will be created between
that layer and the next layer to be added. After the outer hull is laid up,
sheets of balsa coring are fitted carefully into the hull. I imagine these sheets
are compressible, so they are just tightly hand laid next to each other, while
the outer hull is still tacky. After this the “inner hull” is laid
up over the core material using the same process that was used on the outer
hull. Again the laminate layers are saturated with resin until completely wetted
out. Some structural stringers may be laid into the hull near the end of this
process, but most interior structures are added after the hull “shell”
is completely cured. At this point a hand-lay-up hull is left to cure. After
it is cured, it is removed from the hull mold, placed in a rolling jig, and
moved into the assembly process where additional structural components are added,
etc.

With vacuum bagging, when the last
of the layer of laminate has been added to the inner hull, the entire hull is
wrapped with plastic and a vacuum is applied. As the air is evacuated from the
bag, the external air pressure squeezes the laminates together. This applies
uniform pressure to the laminates and I think may result in “squeegeeing”
some of the surplus resin out of the uncured sections of the hull. This is captured
by a filter at the vacuum points.

TPI describes the SCRIMP�
method (an acronym for Seemann Composites Resin Infusion Molding Process)
as follows:
As I understand it, pre-cut and stitched
laminate layers are placed in the mold DRY. (The gel coat and barrier coats have
already been sprayed in as before.) The core is placed in, also dry, then the
inner hull and many structural components are built up. Finally the mold is vacuum
bagged as above, but this time a controlled amount of catalyzed resin is introduced
to the bag (probably from many points). The resin is pulled through the laminate
and core structures by the vacuum, thoroughly wetting out the laminates and core
while all the air is removed from the structure. The entire hull and included
structures cures as a single PRIMARY BOND. There are no secondary bonds between
laminate layers, core layers, or interior structures (like keel stringers). Also,
the amount of resin is very precisely metered, yet all laminate is completely
wetted. This is how the glass:resin ratio is increased. Remember, resin has no
strength, it just serves as a bonding agent for the layers of glass. As long as
the laminate layers are properly bonded, the lower the resin content, the lighter
the structure. A SCRIMP� hull should be lighter for the same strength, or stronger
for the same weight.

TPI had a newsletter on the SCRIMP�
methodology at the ’95 boat shows. If I can find it I’ll check my description,
but I’m pretty sure the general idea is correct. All the J/Sprit boats except
the J/105 have been SCRIMPed. [J/105s have been SCRIMPed since hull 155, ed.].
I always perceived it as a downside to the 105. I didn’t think they’d be able
to make such a big change and keep the class one design. I didn’t realize however
that the boat was already being vacuum bagged, which is pretty close to the
same method. I understand they’ve done a lot of engineering work to keep the
boats the same. For example, the original and Euro interiors were designed to
result in the same fore and aft weight distribution, so neither configuration
would have a speed advantage. Their commitment however is to manage the speed
controlling factors, not factors effecting longevity. I think J/Boats have always
had a history of being long-lived boats, however. They don’t design them so
light that they fall apart, neither are they so heavy that the sailing forces
break them down.

Again, this is my understanding
of these processes. I’m sure there are variations in the actual practice from
my descriptions.

Stuart Burnett

srburnet@rmc.com

J/105 “LEGACY”

Buyer Evaluations

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Owner Testimonials

By Wes Herdman Ladysmith BC on Wednesday,
October 6, 1999 – 01:01 am:

I have cruised my j105 (#30) ever
since We got her 5 years ago. We have spent as much as 2 months at a time on
her. Primarily just myself, my wife and one elementary school age child. We
have at times also cruised for up to two weeks with a second couple on board.
Our cruising area is the British Columbia coast (Canada). We have a factory
installed 2 burner alcohol stove for cooking and have used an ice box or a portable
12 Volt cooler. The electric cooler is an energy hog, but we do not have to
restock with ice every 3 days. With some adaptations in eating habits we can
reduce electrical loads. It is amazing how long yogert will last compared to
milk (or use UHT). Our boat also has a factory installed head with holding tank.
I have made some modifications to the plumbing in order to simplify it.

We as a family find it to be a very
cruisable boat, easily sailed shorthanded (ie only 2 people) under a wide variety
of conditions. If you only race you are missing out on half the fun!!!

More?

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Table of Contents:

J/105 Apparel

Sources for Half-Hull Models

Table and Cooler Mods

Heating and Galley Mods

Wheel vs. Tiller

J/105 Trailer

J/105 Interior Options

J/105 versus J/35

Hand Layup, Vacuum Bagging & SCRIMP�

Buyer Evaluations

Owner Testimonials

Hand Layup, Vacuum Bagging &
SCRIMP�