Mike's journal

My Boat Projects
Last updated: Spring Hill, 23 Dec 2011	Contact:
The projects: Bimini Dinghy Boat Cards Repowering Fridge Next Dinghy

Bimini Project

My first retirement project was a hardtop bimini for Breakaway.  It took a lot longer than I expected but I think it came out OK.  There are two Kyocera 130 watt solar panels recessed into it.  I've connected them to my batteries using heavy 8-gauge copper wire and what appears to be an efficient Blue Sky 2512iX controller.   Here are some photos:   (Click on image to enlarge) The little holes in the corners are for drainage. I made them by building the "grooves" into the sides first, fiberglassing inside the groove, then glassing a "ceiling" over the groove (in the last couple layers of fiberglass).  The curved sections were built up of ⅛" bending plywood laminated over a form, then set in place over temporary supports.  Once I had the 4 sides and middle divider fitted in place, I started applying alternating layers of fiberglass cloth and 18oz biaxial roving until the lip supporting the solar panels was about ¼" thick.  In hindsight, I would have used foam in the curved sections instead of plywood, to reduce the weight a little.   As you can see in the photo below on the right, the bottoms of the solar panels are open.  This should keep them a little cooler and help the efficiency.    (Click on image to enlarge)

 
 

Dinghy Project - Plan

My next retirement project (after I return from Ecuador) is to build a dinghy.  I want to do this in the Abacos, the northernmost islands in the Bahamas.  The Abacos have a long tradition of boat building, including the Abaco Dinghy.  There was a very pretty Winer Malone-built Abaco Dinghy at the boatyard for a while this summer.  The dinghy I plan to build is not going to have those lovely traditional lines, but it should be a lot more convenient for cruising on a small sailboat (much lighter, can be stored on deck, towable).   The dinghy I want to build is from these plans.  It uses the strip-plank construction method.  First, a form or mould is constructed from plywood and 2x4s.  Then 1/4" thick strips of wood are glued edge-to-edge over the mould.  When all the strips are glued together, the bottom is sanded and finished "clear" with a layer of fiberglass cloth (overlapped below the waterline).  Then the form is removed and the inside is sanded and finished clear with a layer of fiberglass cloth.  It looks like this under construction and should look something like the photos below when completed.  I built a 16' Redwood strip-plank canoe when I was in high school.  It was indestructible.   I'm planning to use Spanish Cedar instead of Western Red Cedar (which is what most people use).  I had hoped to use Redwood but apparently it is no longer available.  Spanish Cedar is a little heavier but it should look really nice when done.   Here is how it should fit ondeck on Breakaway..   Here is the dinghy itself (Photoshopped from the lines on compumarine.com)..     Here using a centerboard I prefer a daggerboard to avoid a centerboard trunk inside the boat. I don't know how effective my little kick-up trick would be though. Looks good on paper..   Well, I can use a normal board and experiment with this later. I can't decide between the two versions above. A fairly round bottom - she will be a little tender. Here are some photos from one of the builder's letters from that website..   I like the way he did his seats. This one has been Photoshopped from the original (shown on the left). I plan to make the transom a little curved and rework the seats a bit.     I started to work on the dinghy in August.  I assembled the 2x4s for the strongback and jigsawed the station bulkheads out of 1/2" plywood.  (As they suggest here) I cut and fastened a narrow strip of 1/2" plywood around the edge of each so that I only need to use C-clamps to hold the strips together until the glue sets.  That way I can avoid the little marks left from having to drive staples into the strips to hold them in place.  That took me a couple days, sweating like a proverbial pig.  For whatever reason (age, condition?) I wasn't getting used to the heat.  It wasn't fun.  I had been planning to make the trip to Ecuador and Peru after the dinghy.  Instead, I put the dinghy project aside and set off for Ecuador.  It'll be there when I get back (as I write this I'm looking forward to it).

Update: Man-O-War Cay, 19 Mar 2009 I've added the construction page here.

 
 

Boat Cards

I made up some boat cards in Photoshop and had them printed out on some nice textured business card stock at a little shop a couple blocks from the apartment. I'm "recycling" some images that I found on the web. I edited them quite a bit (and feel I've passed the threshold of "fair use").

 
 

Repowering

The original engine, a Yanmar 3HM35F, has been having some problems lately.  While the base engine and oilpan still seem to be in good condition (it "sounds like a sewing machine" and does run very smoothly), recently I've had   the following problems ... [currently] The engine coolant seems to drop after I run the engine.  The instrument panel plate is kind of old and crumbling on the corners.  The exhaust hose from the muffler to the thru-hull is at end-of-life and needs to be replaced. [0 engine hours ago] The shaft holding the water coolant pump pulley sheared off.  I'm pretty sure the belt was properly tensioned (and it was in fine shape -not showing any signs of shredding or anything- when it happened). [about 2 engine hours ago] There was a transmission leak that came on suddenly and then went away. [about 8 engine hours ago] The high pressure oil line that straddles the engine developed a pin-hole leak.  It is amazing how quickly the oil leaks out under pressure.  I noticed it as soon as it started so the oil level never got too low.  The leak turned out to be up behind the starter and was just producing a fine mist back in that general area.  We had to pull out the engine to find it.  Argh. [about 10 engine hours ago] The raw water entry to the exhaust mixing elbow was clogged up.  It was easy to clear using Muriatic Acid but it's been only about 40 engine hours since being installed.  It was fabricated in Ft. Lauderdale and I'm now not too keen about how it was done. The raw water enters the mixing elbow via a long length of smallish inside diameter pipe with two 90° elbows in it.  Also, the pipe tilts such that when the engine stops, I'm guessing the raw water in it will lie there evaporating (quickly due to the heat), leaving the salt deposited in the pipe.  Argh.  What a bad design.    The current exhaust mixing elbow, fabricated and installed about 50 engine hours ago I don't like the idea of having to clear it so often -every 40 hours is absolutely unusable- especially if it needed it on a passage or someplace where I didn't have acid handy.  Other options are modifying the current one (say, cutting off one elbow and half the pipe) or having a new one fabricated.  All exhaust elbows will eventually clog up.  But a couple thousand engine hours is more reasonable.  The good thing is that it occurred here and now where it was easy to sort out (credit goes to Darren, the Edwin's #2 boat yard manager). [about 50 engine hours ago] The exhaust mixing elbow was cracked (at normal end-of-life).  The local Ft. Lauderdale Yanmar distributor didn't have have anything similar looking in his catalog so the mechanic I had at the time fabricated one from "black pipe".  This part had a problem at 10 engine hours ago (see item above). [about 50 engine hours ago] The Vetus muffler exhibited a small leak where it had been rubbing against the fiberglass of the engine compartment.  It was pretty easily fixed.  But I wonder about a 25-year old plastic part that has been heated up fairly often. The net of it is that I don't feel as confident in the engine as I used to.  I have aspirations of going out cruising again and the thought of having to sail into a strange, squirelly inlet with a broken engine is worrisome.  When the water pump broke recently, I sailed back into Man-O-War harbour and picked up a mooring single handed and felt pretty proud of that.  I swear the inlet was half as wide as normal - juuust squeezing through :-).  But, if I had my druthers, I'd rather avoid that sort of drama.  Then there would also be the hassle and expense of bringing those parts into an out-of-the-way place. The Options I'd like to start with a fresh slate and repower here on Man-O-War where it's fairly convenient.  Unfortunately Yanmar no longer makes an engine of the same HP and weight/size as the 3HM35F.  Here are the vital statistics on the old engine and current models:   Model Nominal HP Max rated HP Continuous rated HP HP/Torque at 80% RPM* Displacement Weight Size LxWxH (in) Transmission Reduction Ratio (forward/astern) 3YM30 30 30 hp at 3600 rpm 27.3 hp at 3489 rpm 28 hp / 50 lb-ft at 2790 rpm 68 cu in 271 lbs 28.2 x 18.2 x 21.5 2.21/3.06 2.62/3.06 3.22/3.06 3HM35F 35 34 hp at 3400 rpm 30 hp at 3200 rpm 27 hp / 53 lb-ft at 2560 rpm 78 cu in 368 lbs 31.1 x 18.7 x 25.1 2.14/ 3JH5E 40 38.5 hp at 3000 rpm 35 mhp at 2907 rpm 37 hp / 80 lb-ft at 2320 rpm 100 cu in 381 lbs 30.3 x 20.4 x 24.5 2.36/3.16 2.61/3.16 Below are the power, torque and fuel usage curves for the 3HM35F, 3YM30 and 3JH5E.  I've plotted the point on the curve for each engine at 80% of peak RPM for that engine* (the red dots).  The (I think, popular) notion is that this is an ideal operating point for each - not over stressing the engine, having some power in reserve, while running it high enough to avoid carbon buildup.  Where it applies, I assume an optimum sized propeller for that engine and RPM setting.  I assume I will need to modify my existing prop.      Here are the power curves.  It is interesting to see how the current generation engines -the 3JH5E and 3YM30- are able to maintain their power at the lower RPMs compared with the 3HM35F.  I assume it's the difference between the latest technology and 25+ year old technology.   (Click on image to enlarge)   The torque characteristics have changed dramaticly since the 3HM35F - both the shape of the curves and the magnitude.  The 3JH5E is billed as "producing 25% more torque than the model it replaces [3JH4E?] from less than 10% increased displacement".  I wonder it that has been a focus for this JH family of engines?     (Click on image to enlarge)   The fuel consumption curves are pretty "normal" looking.  If I run the new 3JH5E at the same "80% of peak RPM" load* (the red dots), the fuel usage should be similar to the existing 3HM35F*.  At that operating point (where remember, the fuel usage is the same) the 3JH5E's RPM will be about 10% lower (so hopefully a bit   (Click on image to enlarge) quieter), engine power will be about 35% higher, and torque will be about 50% higher.  Sweet.  Also, the 3JH5E appears to have other sound-reducing features - a "modified intake silencer" (vs the 3JH4E), claimed vibration reduction and a cover over the V-belt.  It is claimed to have a 5 decibel reduction in noise over the 3JH4E.  A bit about noise.   * -  I'm starting with the "Continuous RPM" rating of each engine for comparison - 3490 for the 3YM30, 3200 for the 3HM35F and 2907 for the 3JH5E.  Then taking 80% of those. * -  I used to run the 3HM35F around 2400 RPM.  At that speed, I figured I was using about 5/8 gallon per hour (by measuring it a couple times).  That looks pretty close to the graph.

Size 14 Sep 2011

Here are front and side views comparing the engines (3HM35F in red, 3JH5E in blue).  The 3JH5E is shown with the KM35A transmission (with the 7 degree tilt).  I couldn't find a schematic for the straight transmission.  I've aligned the front motor mounts.   The 3JH5E (in blue) appears to be a little wider and shorter than the 3HM35F (red).  Pretty good deal for the extra power. The front motor mounts of the 3JH5E are about 3/4" more widely spaced. In my boat, the rear motor mounts are on a special bracket bolted onto the transmission and will probably need some custom installation work on the new engine anyway.   I found this photo online of a 1998 Crealock 34 powered with a 3JH2E.  It looks like that is a 2" exhaust, where the 3JH5E has a (very chunky, but requiring the replacement of everything back to and through the exhaust thru-hull) 3" exhaust.  Anyway, it got me thinking about getting a dripless seal for the propeller shaft and the "high riser" option on the exhaust elbow.   (Click on image to enlarge)

	Prop 18 Sep 2011
		I haven't been able to get a handle on prop size yet.  The current prop appears to be 16" diameter centered in a 22¾" opening.  I'd like to reuse the existing prop, modifying the pitch as necessary.  I am told (by Thumper at Pacific Seacraft) that the latest model PS34 used a 17RH8 prop on what I believe was a 3JF4E engine.  I'll have the local prop shop and Yanmar make their recommendations after I've had a chance to determine the current pitch.
		Here is a plot of Boat Speed vs HP that I compiled from this simple tool.  The tool recommended a prop diameter of 17.9" with a pitch of 10.9".   I'll make some RPM vs Boat Speed measurements for the new engine and my existing prop (and then with any modifications to the prop) and will post the plots here at that time.
		I'll be placing the order for a 3JH5E this week.  Steve Brodie at Pacific Seacraft recommends it and it looks like a good fit.  I started out this section saying Yanmar doesn't make an engine of the same HP and weight/size as the 3HM35F.  The 3JH5E appears to be very close, and generally improves on it.   I'm having Edwin's Boat Yard, a Yanmar Dealer, do the work.  I'm seriously looking forward to seeing an engine hour meter with 0 hours on it :-).  And starting a careful maintenance log for it.

Exhaust thru-hull 22 Sep 2011

The 3HM35F uses a 2" exhaust.  The existing exhaust thru-hull looks like this.  I like the way it directs the exhaust water away from the hull.   The 3JH5E uses a 3" exhaust so I need to replace the existing one.        I was hoping to find one similar to this Buck Algonquin bronze transom thru-hull, but with a threaded NPS end to join to a seacock.  As you can see, this has a hose connection ----->     Here is a printout of the Groco 3" inline ball valve (to scale)   taped to some cardboard to see how it might fit.  It is inserted into a Trident 3" silicon elbow, next to the Buck Algonquin thru-hull.  It doesn't fit very well in the aft compartment [see Oct 3rd update below].   OK.  Plan B is to use a Groco seacock and one of their bronze FTH thru-hulls with the mitered edge that (hopefully) will direct the exhaust water away from the hull.  Here are the relevent sections from their 2011 catalog.   A substantial hunk of metal - weighing in at 34 lbs!   (Click on image to enlarge)

	3 Oct 2011
		Here are the Groco inline ball valve (on the left) and seacock (on the right) scale-drawings-taped-to-cardboard placed in the aft compartment where the exhaust thru-hull is located.   The seacock is much more expensive than the inline ball valve ($575 compared with $300) but has a stainless steel ball compared with a chrome plated brass ball and has what looks to be a much better handle.  Also, I'd have wanted to secure the inline ball valve to the bulkhead (say with a couple stainless steel straps to a block epoxied and bolted to the bulkhead).  A seacock avoids all that mess.		(Click on image to enlarge) Looks like a tight fit.  The thru-hull would have to be relocated from it's old location.  The handle looks like it would be kind of hard to reach in use.  The bend in the exhaust hose (where it comes in from the top) would have to be pretty sharp.		(Click on image to enlarge) Looks like a better fit.  The thru-hull lines up with the old opening.  And the handle should be a little easier to get to.  The bend in the exhaust hose is much better.  Notice how large the new thru-hull is compared with the old one (you can see the threads for the new one on the
				printout).  The old thru-hull was 1½".  The existing 3HM35F installation had the exhaust reduced from 2" at the output of the mixing elbow to a 1½" input to the Vetus waterlock muffler.  So much for exhaust back pressure.  It was producing completely clear exhaust fumes.

 

Fridge

The fridge, an Adler Barbour Cold Machine, stopped working some time ago.  Recently, I bought a new one (a CU-200 with the water-chilling option in case I need it) and am in the process of installing it.  I just saw this comparison from a Practical Sailor article and it made me kinda wish I had gone with a Frigoboat instead.   But on second thought, I wonder.  Breakaway's icebox looks to be about 4 cu.ft. (well under the 10 cu.ft. spec of the Frigoboat) but with probably just moderate insulation - I see about 2½" thickness (including the wall of the engine compartment) where the evaporator's tubing exits the icebox and 1½" thickness on top (including the counter top).  The cover is about 3" thick.  So I wonder if, without adding insulation, the Frigoboat's Danfoss BD35F would have been sufficient?  The article says the BD50F (used in the Cold Machine) has 25% more cooling capacity at 40% more power demand than the BD35F (used in the Frigoboat).  So the Frigoboat's compressor is inherently more efficient.  And it looks like Frigoboat's ability to slow down the compressor to the more efficient 2000 RPM might have been a good fit with my solar panels.   Regarding the BD35F's inherent efficiency, the "25% more cooling capacity at 40% more power demand" claim seems a little misleading.  In that for a given cooling load, the BD50F will run at a lower duty cycle.  If the energy usage and cooling output are both linear with run time, for a given cooling requirement the BD50F would consume just 12% more energy.  Doesn't sound quite as bad. For example:   Say the 35F uses 100 units of power per hr at 100% duty cycle to produce 100 units of cooling. The 50F would use 140 units of power per hr at 100% duty cycle to produce 125 units of cooling. To cool the same amount as the 35F, the 50F would only need 100/125 = 80% duty cycle, consuming .8*140 = 112 units of power per hour.  Or 112/100 = 12% more power. And regarding the Frigoboat's ability to slow down it's compressor to the more efficient 2000 RPM, this might make an interesting Arduino project.  It would be fun to try dynamically changing the resistance in the thermostat circuit to vary the compressor RPM (mentioned under the Sea Frost section), based on the fridge's temperature and contents vs the current and predicted status of the house battery bank.  For example, use the following regimen: Never allow the house bank to drop below 50% charge (to optimize the life of the batteries). Regulate the temperature based on the kind of food to minimize spoilage.  I wonder how you sense milk or fresh food or meat. Set the compressor RPM based on the estimated charge coming in from the solar panels and wind generator - using recent history and a weather predictor.  I think they say using yesterday's weather is a good predictor.  And of course, if it's nighttime we can probably expect not to get a lot of charge out of the solar panels for a while.  Adjust duty cycle and RPM to maintain an even temperature until morning. Warn me if I need to run the engine to supplement the future charge estimated in #3. In general, optimize the available energy to say lower the temperature when there is excess energy available from wind or sun or the engine running (so storing the surplus energy in the contents of the fridge - "make hay while the sun shines" :-), while also trying to maintain a constant temperature when there is not enough energy until the next expected surge. Sources: Solar - Adjust the prediction for the changing seasons - ie. summer vs winter.  Make a prediction about the cloudiness and effectiveness of the panels as the boat swings.  If the panels seem to be shaded by the boom, warn me to move the boom to one side (recommending which side). Wind - Adjust the prediction to wind patterns.  E.g. I may be in a spot where there is a land/sea effect cycle - where the wind picks up in the morning and evening.  Or I may have temporarily moved the boat out of a protected calm area like up a river to an open windy area like offshore islands.  Engine's alternator - Adjust the prediction for say, my being away from the boat and not being able to start it up.  Or a period where I run the engine regularly - say an hour each day to move from the anchorage to a swimming spot and back - something we used to do each day on the Rio Dulce. Also, the CU-200 has the option to add a "Water Cooled Option Package" (looks like currently around $435 online).  The CU-200 installation manual claims that with it, "In tropical conditions, the total daily power consumption can be reduced by 25%-40%".  I plan to stay in the tropics so it may be worth adding.  The Frigoboat has air cooled, water cooled and the "keel cooler" options.  But they appear to be just one at a time - not in combination like the CU-200.  The CU-200 + Water Cooled Option does add another pump (something to break down) to the boat.   I wonder which of these various options is most cost effective in tropical conditions?  Hmm.  I'd like to measure my current system (new solar panels, new fridge, 3 year old Deka 6v battery house bank that has never been deeply cycled and has been equalized once just recently) in use to see how well balanced it is and how much fine-tuning it is going to make a difference.  Still, I think I'd like to try the resistance-varying trick just for fun.

	Man-O-War, 10 Oct 2011
		On a day with around 80°F temperatures, the new fridge (half full, with 3 trays of frozen ice cubes), is averaging 3:10 (min:sec) on, then 10:15 off.  For about a 25% duty cycle.

 

Next Dinghy Project - Plan

I'm thinking about building another dinghy.  Following is the start of planning.  Or skip ahead to the construction page.
 
So, why another dinghy?  First, a picture.  The red hull/green lines are the 10' nesting Spindrift dinghy that I'm considering.  The black lines are my existing 9' Yacht Tender.  The rolled-up gray thing on the bow is my existing Avon inflatable.  I'll probably sell the Yacht Tender and keep the Avon for a backup.

1. It looks like it would fit better amidship, where the Yacht Tender will interfere with the main sheet.  On the bow, both interfere with use of the staysail as well as tacking the genoa when the staysail is not in use (and the inner stay is moved to it's aft storage position - where I usually keep it).  Also, it looks like it will be a little "shorter" on deck, so should be easier to see over.
2. It looks like it should have better initial hull stability - making it more convenient for passengers to board and easier to transport bulky/heavy stuff like 6 gallon jerry containers of fuel.
3. It should be able to take my existing 4 HP Johnson outboard motor where the Yacht Tender (1) requires a long-shaft outboard and (2) doesn't appear to have as much bouyancy in the stern to take the weight.
4. It looks like it should plane.  The Spindrift webpage shows a 10' model planing with a 2 HP engine (with a fairly lightweight boat driver).  An online forum mentions planing under sail (again under ideal conditions).  Pretty kewl.
   17 Jan 2012: I just noticed on one of Garry Prater's pages, he says:
   She reached a plane a few times and once on a broad reach with a gust she took off on a plane like a shot with a slight hum from the centerboard. Wow!
5. I would paint the Spindrift.  It would then be easier to maintain and I wouldn't worry so much about knocking it against docks and rocks and such.  Just a matter of applying some fiberglass and fresh paint over the damage.
6. It would draw less attention and not set me apart as much from the local community.
7. Not sure if it would be practical, but it looks possible to launch by placing each half in the water and assembling it there.
   25 Dec 2011: Garry Prater, who came up with this idea, described to me how he was able to join the two halves in the water and how he did that once in gale-force winds in an emergency - when he had to launch his dinghy to carry out an anchor in the Intracoastal Waterway during a sudden storm.

Designer	Design	Len x Beam	Weight (lbs)	Capacity (lbs)	HP	Rig/SA	Notes
Danny Greene	Chameleon	10'4" x 4'2"	~100	~500	2 - 4	Lug / 50 ft2
Chesapeake Light Craft	Eastport Nesting Pram	7'9" x 4'	75	375		Lug / 42 ft2
	Passagemaker Dinghy	11'7" x 4'8"	94	650		Sloop / 78 ft2
David G. Bolduc (based on Matt Layden)	Micro Folding Dinghy	6'10" x 2'+
							Uses 1 sheet of ¼" plywood + a little canvas. Free plans.
Nestaway	8'2" nesting pram	8'2" x 4'3"	100			Lug /
	8ft Nesting Stem Dinghy	8' x 4'	75 - 80	400		Lug /
	9ft Nesting Clinker Stem Dinghy	9' x 4'3"	110		2.5 - 4	Lug/
	10ft NN10 Nesting Stem Dinghy	10'2" x 4'5"	145			Sloop /
John Holtrop	Nestor 8	8' x 3'8"		2 adults		Cat /
	Nestor 10	10' x 4'4"	80	4 adults		Cat /
Port Townsend Watercraft	PT Eleven	11' x 4'2"	85	518	2	Cat / 60 ft2
							Forum: Builders' BLOG
B&B Yachts (Graham Byrnes)	Spindrift 9N	9' x 4'1"	72 - 82		2 - 3	Cat / 45 ft2
	Spindrift 10N	10' x 4'2"	77 - 87		2 - 3	Cat / 55 ft2	Forum: B & B Yachts Forum Construction pages: Building a Spindrift 9ft Nesting Dinghy, Expedition Dinghy, Building a Spindrift 11s
	Spindrift 11N	11' x 4'6"	88 - 110		3 - 4	Cat / 65 ft2
Wooden Widget	Stasha	7'2" x 3'8"	22 !	330	max 3.3	Lug / 25 ft2
							There are several folding designs on their website as well.

Here is a comparison of two transoms - the Spindrift in red, the Port Townsend Watercraft Eleven in white.  The Spindrift, with just the one chine, looks like it will have a little more form initial stability.

Again, here is my construction page.
 

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References:    Source of the Yanmar 3YM30 and 3JH5E curves    The 3HM35F curves and other specs are from the Yanmar service manual    All the 3JH5E manuals    Compass Marine "How To" Articles - lots of photos, clear explanations    Here is an interesting look at the inside of a mixing elbow after 2000 hrs    Free small boat plans - canoes, dinghies, small sailboats, houseboats, etc