Friday, January 30, 2015

Battery Voltage Monitor

Our Tartan 3500, Intuition, hull number 115, has the standard battery voltage and amp meters installed in the nav station.  Since purchasing Intuition, one of the mysteries is determining when to charge the house battery.  The general guideline is don't deplete battery more than 50% charge.  However, there's gotcha's with this, in that the battery voltage needs to be resting voltage.  For our first few years of ownership, I monitored the voltage according to this chart,

My general guideline was 50% charge is reached when open-circuit voltage is 12.32 volts and the load voltage is 11.8 volts.  In practice, this is difficult to monitor when sailing or at anchor, with refrigerator and/or electronics running.

When sailing on an extended delivery on a friend's boat, he monitored the battery bank usage with a Link Pro Battery Monitor,

These gauges provide

- Main and aux battery voltages
- Amp draw
- Accumulated amps used
- Percent capacity remaining
- Alarms

I was hooked - no more guessing when to charge!! 

In researching battery monitors, there are a few suppliers: Xantrex, Victron, and others.  I decided on installing the Victron BMV 702.  This item came with all necessary cables and was less expensive than the Xantrex. I also read that folks have had problems with the Xantrex units, while feedback was generally excellent for the Victron.  

The way these gauges work is that a shunt is installed between the house battery and boat's common ground, along with +12 volt probes on each battery.  As electrical items draw amps from the battery, the current runs through the shunt and the battery monitor measures the voltage drop.  This voltage drop is converted to amps and accumulated by the gauge.

Installation was pretty easy.  There were several items to address to install.

I needed to find a suitable location for the shunt. I decided to put this next to the DC ground bar.

My next challenge was that my house battery had several ground wires connected directly to the house battery.  Since current through these wires or cables don't pass through the shunt, their amps would not be measured by the monitor.  One cable that caused me to think through Intuition's wiring was the DC ground from the Link 1000 battery charger and inverter. After thinking about this for a while, I decided to move the black cable (ground) from the Link 1000 to the DC common bus.  This required ordering two custom 00 gauge cables with the proper M8 and M10 ends. I find it odd that the shunt used M10 sized bolts, while the negative battery terminal and ground use the smaller M8. I also moved the ground for marine ssb/ham radio.  Now all the grounds are on the common DC bus and pass through the shunt.

Next, I needed to decide where to install the gauge. Installing the gauge was very easy - all it required was a 2" mounting hole.  It was pretty painful to drill this 2" hole in our nav-station.  I didn't have much choice as to where to install the gauge.  I went for it and drilled a 2" hole, mounted the device.

One of the advantages of the Victron BVM is that an RJ11 cable is used to connect the shunt and the gauge.  Connecting the wires was very easy - snake the RJ11 cable through the conduit and plug into the back of the gauge, just like a telephone.

Setup only requires setting the house battery capacity and what feature to monitor on the 2nd battery - I chose volts.  The gauge defaults to 200 amp-hours.  I changed this setting to 300 amp-hours.  I also disabled the 'watts' display.

At this point, I thought I was done and began celebrating!!!  Like everything on a boat, there's always something that goes wrong.  I turned on the boat's electronics and the gauge measured positive amps (great) BUT NOT any accumulated amp-hours (not great).  I let the gauge accumulate amps for about a 1/2 hour hoping it would begin registering. It didn't.  I thought for sure I had a bad gauge.  I was not happy.

After reading the manual for the 10'th time, I found one-sentence that clued me in to the problem,

Charge amps are positive, e.g., putting amps back in the battery, and consumed amps are negative, e.g., using amps.  I had the shunt wired backwards...  A quick fix, swapped the cables and noticed amp-hours increasing with usage.

How did this happen - when installing the shunt, I decided to flip it over so the RJ11 and battery wires are plugged in from the top.  That effectively flipped the battery and ground connections.  Because of the delay in ordering the custom cables, I forgot about this last-minute decision.

This is the single most useful gauge on the boat, even more so than fuel (since we rarely use diesel, but always are using battery).  In practice, knowing that we have 300 amp-hours, it is very easy to check the accumulated amps.  When approaching 150 amps consumed, it is time to charge the house bank!

I find it a bit difficult to view the LCD display.  Like most current electronics, the display is very small and is backlit with blue LED.  This is a minor concern, since the accumulated amps is so important to monitoring  your battery capacity.

Don McLennan
Intuition - 3500 - #115

Tartan 3500 - Rebuild Cabinet V-Berth

A few days into our bash back from Cabo San Lucas, the cabinet frame under the v-berth shifted away from the fiberglass frame and pressed against the frame of the closets.  With each wave, the v-berth sounded like it was breaking apart. While underway, I managed to hold the front-panel in place with a wood-block, between the closet and front-panel.

Here you can see the frame pressed out about 1 1/2".

In looking at the construction, the front frame was held in place by 6 screws from the backside into the plywood frame.  Obviously, these weren't sufficient to hold the frame in place.

My solution was to add a spacer block to the inside of the front-panel and use large fender washers to secure the panel from the back,

With the spacer block in place, I secured the front panel with longer screws and large fender-washers,

I ran a bead of silicon around the entire frame, to provide a bit of insulation and to hold the panel to the fiberglass, and larger screws to hold the sides in place.

Intuition - 3500 - #115

Portlight Gaskets

When bashing back from a recent trip to Cabo San Lucas, I discovered that our portlights did not seal very well and sea-water leaked into the boat.  Unfortunately, this was most noticeable from the v-berth portlights, and soaked both closets and their contents.

On Intuition, 2000 3500, #115, the portlights are supplied by Manship, LS Stainless

The replacement gasket material is 7122 at $6.03/ft.  and only seems to be available through Marine Depot Direct.

Intution has 10 portlights,

6 @ 10 1/2 x 4 1/2      15'
4 @ 15 1/4 x 5 1/4      14'
Order 4' extra          4'

Total                   33'

7122 @ $6.03/ft =   $198.99

Wow, that adds up pretty fast.

Looking for alternatives, I found Wefco Rubber, here in the San Fernando Valley which makes custom rubber.  The size needed was 3/8" round by 7/16", with an inside diameter, at less than $2.00/ft.

Installation was tricky.  The rubber from Wefco was a harder than the seals removed from the portlights.  This made it somewhat difficult to press into the frame,

I used SuperGlue to glue the ends together. On the larger portlights, I needed to use a drop or two of superglue to hold the rubber to the frame.


Notice the compressed and malformed rubber?


Since the rubber is harder than expected, at first, it was somewhat difficult to close the portlights.  I found that by loosening the set-screws on each hinge, it became easier to open/close the portlights.  After about a week, the rubber began to conform to the frame and now is much easier to open/close.  I'm hoping that after a while, all the portlights will get easier to open/close.  The rubber does seem to be conforming to the frame, so I'm optimistic.

When talking to the folks at Wefco, I didn't realize the rubber would be harder than what was on the boat.  Consequently, I ordered an 1/8" inside diameter hole, with the idea that this would provide more rubber to conform to the frame.  Note in the before picture above, the rubber is pretty misshapen and in some cases torn.  I thought that extra rubber on the face would help!

Time will tell - I'm 85% optimistic that this will be OK, the portlights will seal and will be easier to open/close.  The funny thing - about 3/4's of the portlights open/close nicely, while the others are a bear to close.  A good hot S. California summer should do the trick!

Intuition - 3500 - #115

Tartan 3500 V-Berth Shelf

Intuition, our 3500,  has a lot of areas that are ideal for storage. One area is directly under the v-berth.   Unfortunately, this space is not very usable since the water hose runs right down the middle of hull . The solution, build a shelf.

This is my second version of this shelf.  The first version was attached to the back-side of the cabinet.  I believe this placed extra force on the cabinet frame, aiding in it becoming broken from the frame.

Instead of screwing into the frame, I made a separate frame out of 1" x 3", contoured to fit the interior shape of the hull, with a mortised 1" x 2" cross-member.

My theory is that the frame will rest against the hull.  Any weight on the shelf will press down against the hull, and not the back of the plywood cabinet.

And used another 1" x 2", thru-bolted to the back of the plywood cabinet, to keep the shelf from lifting,

The shelf is secured to the 1" x 3" frame.  And the final set of shelves,

I did put a small lip around the shelf to keep items from rolling off the base.  I may decide to box-in the front and back areas, so items don't fall into the bottom of the hull.

Final, useful storage,

I don't expect to put heavy items on this shelf.  Specifically, we can store the ditch-bag, first-aid kit, life-jackets, and other soft/loose items.

This provides a lot of useful space that is easy to access. So far, I'm pretty happy with this enhancement.

Intuition - 3500 - #115

Marelon Seacocks

We had a near catastrophic situation when after a nice day of sailing, I went to close the head seawater intake thruhull and the handle popped off in my hand.  Sea-water immediately started flowing in.

The handles are secured to the seacock ball by a 3/8" screw.  There's also a o-ring around the shaft of the handle and the screw to seal the seacock.  After the handle pulled out of the valve, I tried to put the handle back into the valve, to stem the flow of water.  I discovered that the o-ring became dislodged and pressed into the body.  This prevented the handle from seating into the valve.  Meanwhile, water keeps pouring in to the boat.

Using a small screwdrive, I removed the o-ring (all while water is pouring in), reassembled the handle and was able to properly insert and secure.  This is a terrible design, though I guess it lasted 14 years before the threads wore.

The solution turned out to be very easy.  I obtained 2 replacement seackcock valves from Forespar.

Notice the valve is made in 4 sections, held together by 4 large bolts from the top.  There's the threaded thuhull (white, not shown), that screws into the 3 1/2" diameter base, ball valve assembly (middle, where handle is attached), and top assembly.

Forespar's new design uses an embedded nut and bolt to hold the handle to the valve (I checked).  This should be more secure than the 3/8" screw.  Otherwise, the valves are identical.  What that means is you can replace the middle section, and don't have to haul the boat to replace the thruhull!!!!

Notice the white plug on the handle (above)?  It turns out this is the proper size to fit the thruhull from the outside of the boat.  I guess their idea is if the handle breaks off and the boat is sinking, you can jump in the water and plug the thruhull with this little plug.  Right..... I had my diver plug these, the next time he cleaned the bottom.

With the thruhulls plugged, I cautiously took apart the seacock,

Pay attention to the squarish gaskets between each of the marelon pieces.  Per the instructions, I applied a bit of marine grease to these and reassembled.

One final note, the seacock clearly states to not disassemble the valve,but Forespar's technical support encouraged me to do exactly this!  It is great when the design is improved and the parts are interchangeable.  It would have been just my luck if the assembly was 1/8" different is size or the screws were moved.

I replaced both the smaller sea water intake seacocks.  I'm relieved that these are operational without the fear of the handle coming off and flooding the boat.  The fix was very easy.  I'm thinking about swapping out the ball-valve on the remaining 3 seacocks in the boat.

Don McLennan
Intuition - 3500 - #115

Battery Usage

In evaluating our house battery capacity, I put together this table of item and amps consumed,

Total Amps
Interior LED Lights
Navigation LED Lights (Sail)
.1/each, .2/all

1.5 ß may swap out with LEDs


0.8 (*)

1.0 (*)

Autohelm Linear Drive
2.0 – 4.0 (*)

VHF Radio Receive
0.5 (*)

VHF Radio Transmit

SSB Transmit
3.0 (LOW)

4.0  (*)

1.0  (?)

Cabin Fans
1.0 (?)

Macerator Pump



An example of using this information, when using the items marked with an asterisks (*), it is reasonable to expect Intuition to use between 6 and 8 Amps per Hour, depending on the cycling of the refrigerator and autohelm linear drive.  Assume 6 Amps per Hour.  Over 24 hours, we'd consume 144 AmpHours, or about 50% of our house battery capacity.

Note - each of the original incandescent interior cabin lights draw about 1 Amp.  I replaced all of them with LEDs, and the total is 2.5 Amps!  Likewise for the navigation lights.  I have not replaced the anchor-light, but that's next on my list!

It is interesting that even with 300 AmpHour house battery bank, I only have enough capacity to keep the boat's electrical usage for 24 hours.  On multiday sailing, we need to charge the house battery bank every day.

Don McLennan
Intuition - 3500 - #115

Windlass Remote - Experiment

Recently I've been having problems with one of my windlass foot controller switches.  The problem stems from the base not properly sealed against the deck.  This allowed sea-water to seep into the switch mechanism and corrode the contacts.  Previously, I tried cleaning the contacts, which was a temporary fix.  I eventually replaced the switch and properly bedded to the deck.


In looking around options for controlling our windlass, I've been thinking about a hand-held remote.  There are wired versions, particularly the Quick  HRC remote, which retails for around $100.

This is pretty slick and would work well in the anchor locker of our Tartan 3500.

There are various wireless remotes.  Pictured is the Lewmar remote, starting at $250.
There are also inexpensive wireless control units found on eBay. These run between $13 and $20, some include two remotes, others a large remote and keychain remote, and this one claims to be waterproof!  I couldn't pass up this experiment.

Surprisingly enough, the remote is pretty solid, with a good feel to the on/off button and the up/down.  The receiver is of comparable quality to other electronic gadgets in plastic cases, found on the boat.

If this works, I'll be very happy with his purchase.  For the price, it is a noteworthy experiment.


Wiring is pretty straight-forward,

Red - plus, which connects to the positive lead on the windlass switches.

Black - negative, which connects to the windlass ground

White - down

Yellow - up


Since the size of the receiver is small, it measures about 3" x 2" x 3/4" and is very light, I decided to tuck up under the deck by the windlass control switches.  As a temporary measure, I simply wire-tied to the wire conduit.

I turned on the windlass main breaker and the handheld remote - pressed the down button - after about 1/2 second delay, the windlass engaged properly in the down direction. Likewise for the up direction.  Now I need a lanyard for the remote!

For $15, I could replace this every year and still be ahead of the dedicated marine units.

Don McLennan
Intuition - T3500 - #115

Deck Latch Tartan 3500

Our Tartan 3500 came with flush mounted cylinder cam locks on the anchor and propane lockers.

When we first bought the boat, these were corroded beyond repair. I tried soaking in kerosene, vinegar, fresh water.... but could not free the cylinders.  I even purchased a replacement set from Tartan.  These locks were manufactured by Accon Marine and from what I can tell are only suitable in a non-marine (salt-water) environment.  The locks are of poor quality and only lasted a few months.

What a challenge to find the right latch - I finally found the perfect replacement.  As much as I wanted the square frame, I ended up going with a round compression lock that claims to be waterproof and resistant to salt-water, corrosion.

There were several challenges – my anchor locker deck thickness is 15/16”; propane locker is 1 ¼”.  Many of the locks are limited by the deck thickness of 13/16” (.88).  To add confusion, the offset to the mitered groove in the locker is 2 ½” and propane locker is 1 ¾”.  I need adjust ability from 1 ¾” to 2 ½”.  Then there’s size of the arm, though I could always cut it shorter.

What finally influenced my decision was the Gemlux online calculator,  

After spending too much time looking at the mechanical drawings and technical specs for several of these latches, I found their calculator and voila -  they have a flat plate for thicker decks, and various shaft lengths and cams. 

Customer service was outstanding and very patient as I sorted through variables such as deck thickness, grip, cam length, offset,.... Although I wanted the similar squarish flat frame, the sales guy at Gem Products told me that the square locks are fading and people are going with these compression locks.  Claims to be waterproof, which hopefully will keep my anchor locker dryer.  Amazing customer service.  I'm looking forward to finally having a secure anchor locker.

Installation should be pretty easy.  These locks require a 2" diameter hole cut in the deck, using a hole-saw.  This seems a lot easier than cutting odd-shaped holes for shaft, routing out the recess, etc. Now that I found the proper configuration, it should be very easy to install.  

Intuition - Tartan 3500 - #115