Houseboat Stability

Seattle house barges are a gem of lakefront living and certainly a very special lifestyle for those who choose to love them.  The alure of the custom architecture, the instant access to kayaking or boating, the close knit neighborhoods which make you feel like you are living in a small town, all of these factors draw Seattle residents to Lake Union living and I have very much enjoyed working with these customers.

One issue that has come up on a few surveys of these magnificent floating homes is that of stability.  This is a topic which is often forgotten but of great importance especially during home remodels or for homes which have never had these calculations done.  Vessel stability is quite simply the factors that go into the angle of heel (how the barge leans side to side) and how this relates to final vessel trim as it sits in the water.  It probably does not need to be said that disregard for barge stability can have negative consequences but often stability issues can be easily remedied with a solid plan.

Stability graph for different angles of heel.

There are two main factors to consider when planning for stability, static and dynamic forces

Static – Static forces are  those related to the distribution of the mass of the boat.  Ballast (weight added for stability), structural height and width, weight of building materials, etc.  This is an interesting calculation as we don’t get to take the boat apart and weigh each component so surveyors conduct a heel test with calcuations in order to accurately model the static forces.

Dynamic – These are forces which change over time and might include tank water sloshing, a large number of guests on the rooftop deck or even a winter storm cross breeze pushing on the exterior wall.

Overall there is a lot to consider when dealing with the stability of your house barge.  How the center of bouyancy changes given the shape of the hull, how the center of gravity relates to all else to create the righting arm (the force that rocks your boat back upright).  All of these factors go into calculating a number of figures which inform the current state and safety of the home and reveals great info about the stability of the barge.  If you are super interested about the specific of these then feel free to contact me and I can send you some more detailed info but for now I am trying to prevent this article from becoming a Naval Architecture textbook.

Stability Tips:

  1.  Consider getting a stability survey – I have to say this first of course as getting professional help on this matter is the best way to have a great plan.  Keep stability in mind especially if you are planning additions to your floating home.  A stability plan can help to make sure your project results in a fully functioning and safe home.
  2.  With a shallow draft barge hull that is common for house barges, simply adding more ballast does not always help.  I did some consulting on a very narrow and tall houseboat that the owner had been adding a huge number of concrete sacks to the bilge for ballast but with no change to the shockingly slow roll that the boat had.  With calculations we were able to determine in this case that his placement of ballast was reducing the metacenter of the boat slightly faster than it was reducing the center of gravity.  To paraphrase, his ballast plan was actually a detriment to the stability of the boat.  An easy plan was made to solve the ballast issue.  Ballast is normally as low as it can be and with shallow draft house barges this sometimes means the ballast is under the barge rather than in the bilge.
  3. Ballast should be secure in place.  Loose ballast will tend to shift when it is being most challenged by dynamic forces with the effect of making things a lot worse.
  4. Avoid using uncured sacks of concrete as ballast.  It is a cheap soluction but powder concreate is a chemical which becomes hot and caustic when wet and these factors are not good neighbors for your hull.  I have seen these concrete sacks sitting inside wood hulls with severe degradation in the area where the concrete bag was sitting on the wood hull.  I have also seen lead tire weights in use as ballast and this material can tend to leach toxins into the bilge water where it eventually gets pumped overboard.
  5. Stability considerations are not only for the tall, high risk barges.  If your boat has a fast and uncomfortable roll in weather that tends to make your guests uncomfortable, then a stability plan can actually help slow this roll down while still maintaining ultimate safety.  Recommendations might include ballast, trim weights, outboard floatation, flopper stoppers, and a number of other tactics to dampen the roll.
  6. If you are replacing or doing significant work on an old wood or fiberglass over wood hull then consider replacing the hull with a lightweight and wider footprint aluminum hull.  They last a long time and often this change tends to add significant additional stability AND value to the boat.

If you have questions in general about houseboat life then you can contact Kevin and Linda Bagley at Special Agents Realty, two people who have been a tireless supporter of houseboats in Seattle and knows everything there is to know about them.

I fostered a great interest in this question while stationed up in Juneau, Alaska for the US Coast Guard.  One heavy snow storm up there resulted in two houseboats having major stabity issues due to rooftop snow load and the additional weight this caused up high on the barge.  After the snow was removed and the houses made right again I was able to help these owners create a plan to keep their homes safe for the future considering all dynamic loads to be expected in Alaska.  This is a topic for which I have great passion and If you have questions about houseboat stability then feel free to contact Eric at Tasman Boat Company.

Winter Warmth Aboard, Sometimes a Little Too Hot

With Seattle winter in full swing and a couple of cold snaps of snow already in the log book it pays to talk about space heaters.  It is common for boat owners to use cheap little electric heaters to keep their boat interior dry and to prevent frozen pipes.  The fire department and your insurance agency would like to remind you that plugging in a space heater into a power strip not rated for such high amp loads is a highly risky action.


Power strips aside, any space heater should be of high quality, have a wide and stable base, should shut off automatically when tipped over, and not be a risk for falling paper or other combustible goods catching fire.

As a surveyor and a former US Coast Guard marine investigator, I have seen all too many of the cheap foreign space heaters catch fire all on their own.  The culprit of these fires was not what you would think (the heater element) but rather the overheating of the poorly constructed printed circuit board which controls the unit.  So I would recommend that you get a high quality unit or better yet intall a marine electric heater system onboard to maximize safety.

Happy boating!!


Pre-underway Checklist

I have been asked about what specifically needs to be done in order to get a boat underway in order to maximize safety, minimize issues and help the crew enjoy the day.  Unfortunately the answer to this question is as diverse as the number of boats on the water but I will start with a general list for sailboats mainly because most of the recent questions came from new sailboat owners.

This list is a work in progress and will be updated periodically.

Things you should keep in order at all times:

  • Charts of the area to be navigated, navigation gear and knowledge
  • Vessel registration and all safety gear (PFD’s, fire extinguishers, flares, horn, etc)
  • Inspect your anchor rode for wear and make sure the stainless siezing wire holding the shackle is in good order.
  • A means to recover crew from the water (lifesling, boarding ladder, etc)
  • Test bilge pumps
  • Navigations lights in working order
  • Boat hook
  • First aid kit
  • Engine gauges are in good working order, depth sounder functioning
  • Tools appropriate for anything you might need to work on while underway
  • Sunscreen, hat, polarized sunglasses
  • Appropriate clothing to keep warm (it is often quite a bit cooler out on the Puget Sound than in town)
  • Binoculars
  • Drinking water


  • Float plan – Let someone who cares about you know where you are going, when to expect you, what communications devices you have and what to do if you don’t report in.
  • Check weather report
  • Inspect running and standing rigging, remove sailcovers and inspect sails
  • Open raw water seacock
  • Open fuel supply valve
  • Inspect engine belts, hoses, evidence of new leaks
  • Check engine oil each time before starting, check marine gear oil and fuel injection pump oil about every 2nd or 3rd time starting the motor.  Check belt tension.  Verify coolant levels and top off as needed.
  • Turn off shorepower switch inside boat and at the dock and disconnect shore power cord.
  • Turn battery switch to the appropriate setting for starting
  • Turn on engine instruments if this is on a seperate switch
  • Activate any appropriate fuel lift pumps as required for your boat
  • Preheat engine as required by manufacturer
  • After engine starts check for raw water flow at exhaust, stop engine if no flow and repair as needed.  Then check gauges and inspect motor now with motor running to verify that all looks normal.
  • While motor is warming up you can spend some time bringing online the VHF radio, autopilot breaker, stow the shorepower cord, unlock the helm, remove instrument covers, unlock hatches and lockers, verify manual bilge pump lever location, brief crew on the plan, do a dockside marine transmission test.
  • Always remember to check up and down the marina fairway for other boats before casting off lines.

Yanmar 1GM Rebuild

So the current challenge for me is to get a 1980’s Yanmar 1GM running.  I got this engine by helping a client remove it from his recently acquired 1930’s Dutch built wooden sailboat and the owner before him had really abused / neglected this quirky but popular little workhorse for a number of years.  For those that don’t know, the 1GM is a single cylinder diesel motor which can be found in a number of small sailboat in the US and abroad.  They have some known issues but overall they work well if you take care of them.  And taking care of this specific example is exactly what did NOT happen.  When my client had this boat shipped in it was with the hope of getting rid of this motor in favor of a nice electric setup and it was clear why.  The motor was caked in rust (Yanmar paint is known to fail fairly easily), did not run and it was clear that it lacked full compression.  We got the engine out no issue except for the siezed engine mount nuts which meant that the motor came out with the mounts still attached.  Now that I have broken the motor down here is the list of items wrong with the motor:

Failed paint – Yanmars have a thick metalic paint which seems particularly prone to fracture and rust.  Combined with the cast block and you don’t really have a recipie for an engine that will forgive lack of maintenence.  This will need to be cleaned up and repainted.

Thermostat completely siezed with rust – The thermostat was completely rusted and fouled with deposits such that there is no consideration that it might be saved.  Into the garbage it goes!

Clogged cooling channels – This is a common issue with the Yanmar GM line.  No real damage to be seen as a result of this but it sure is a pain to get all of the deposits out.  I did not find any rusted through parts of the head channels which was good since it does happen.

Carbon scale in the exhaust ports – Carbon scale essentially gets baked on to the inside of your engine and is more difficult to clean that getting burned cassarole off of a baking pan.  I used a chisel very carefully on the surface of the carbon to see if I could get it to fracture which most of it did.  Lastly a dremel tool with a sanding brush light enough to not damage the metal made quick work of the leftover carbon.  This is an issue that only gets progressively worse over time such that eventually the motor will have so much backpressure that it will not run.

Exhaust valve erosion and carbon buildup – Because the exhaust valve had been fouled with carbon it was allowing the explosions to blow past the partially open valve.  This sacrifices engine power but also causes a burned valve via hot gas erosion and fatigue.  A new exhaust valve is so cheap that I will most likely just get a new one but I am at least attemping to see if I can lap the seat with a nice silve edge all around the valve and seat contact seal.  Doubt it but it is fun to try.

Exhaust bend mounting face on the head is rusted and will not seal – This is the gasketed joint between the head exhaust outlet and the exhaust elbow.  It is held on by three bolts at basically 9, 12 and 3 o’clock while 6 o’clock is unsupported.  I have no idea why they did this as there is room for a 6 o’clock bolt but I digress.  At the 6 o’clock position there was a past water leak coming from the unsupported side which turned the seal face into a rusty mess.  This probably means that the head itself is done for by most standard but ultimately I am not interested in paying hundreds of dollars on a new head and am more interested in making the old one work for the challenge and engineering of it all.  In my mind there is no real reason why a thick sturdy pipe can’t be welded on in order to be rid of the pesky rusted seal face.  If it needs service in the future then it can be ground off and I am totally ok with this versus buying a new head.

Exhaust elbow – This is a famously pesky part on these engines, pretty much guarenteed to fail like clockwork every 4 years.  And at only $300 a pop from Yanmar (granted it is a double wall tube but I still think that is a lot).  I am planning to duplicate the same thing in a more durable setup and simply weld it straight to the head.  It pays to mention that in order to weld to a head you have to know what you are doing or you will certainly just crack it.  For those of you who own this engine it is advised that you remove the exhaust elbow every two years and really just consider replacing it.  Failure of the water and exhaust mixer causes water to spray backward into the head with often pretty disasterous results and it is best to just avoid this.  You can find quality aftermarket examples in stainless steel for about a hundred bucks.

Overall a fun project engine and one which I plan to get chugging for about a hundred bucks.  It won’t be perfect but the goal right now is to consider installing it in our 14 foot cocktail launch built in the 1940’s, no round the world cruises with this motor.  The launch currently has an air cooled gas flathead engine which is unbelievably loud and despite being a reliable engine this noise is something that I would like to get rid of even if it means dumping the Kohler engine.  I have looked into mufflers made for it but the engineer seems to only think this will take care of about 20 db of sound so we have only gone from 747 engine noise to only a race car engine noise level, yea!!!  With a small water cooled diesel the motor could be mounted inside a sound proof enclosure where the engine noise goes out through a water muffler and the mechanical noise gets taken care of by the insulated enclosure.  And maybe, just maybe, my cocktail guests will be able to take off the hearing protection and actually converse with each other!!  One can always hope.

Happy boating to all!!!


Heat Exchanger Zincs

We can’t expect everyone who buys a boat which is new to them to know absolutely everything about that boat and often the previous owner is not around to show you all that needs done in order to keep up on maintenance.  One easy maintenance item are the “pencil zincs” inside of 99% of heat exchangers.  The heat exchanger transfers waste engine heat from the coolant loop to the raw (or sea) water.  Because it is metal and in contact with salt water we need to take special measures to protect the heat exchanger from corrosion.  This is accomplished mostly through small zinc anodes which are inserted into a threaded port on the exchanger.  It surprises me how often boat owners have no idea that there is something about the exchanger which needs any service much less regular service.

Below is a photo taken from the online Sailboat Owners Forum:

Heat exchanger

When pencil zincs are left too long there are a number of things that happen.  Most importantly they will loose their protective capacity over time and they will break off and tend to clog the exchanger channels.  This condition will slowly allow damage or corrosion on the heat exchanger itself and will result in having to limp home and a costly repair bill.

I recommend everyone research the different maintenance items required to keep your investment in good working order and if you don’t have any idea of where to start then give me a call and we can set up a time to have a knowledgable person come onboard to make a maintenance checklist.  At Tasman Boat Company, with a survey report we generally include a link to appropriate engine manuals if one is not found onboard and provide any consulting needed to help the new owner understand how to keep things running.  This extra step helps the proud owner get through that first year without any user error caused damage and we always like to hear stories of successful boat ownership.

Happy Boating!


Copper Bottom Paint and the Puget Sound

On 1 January 2020 you will no longer be able to find anti-fouling bottom paint which contains significant amounts of copper at your local marine store.  Copper bottom paints have been the standard for marine bottom coatings for decades but new research suggests that copper levels are rising.  A 2007 study found that copper is pretty toxic to marine life and causes salmon to lose their fight or flight survival reaction to danger.

Clean Boating Foundation

Don’t despair, marine coatings companies have been hard at work to develop products that they argue work better and are better for the spectacular marine environment in which we live.  Tasman Boat Company is in the process of aquiring samples of these coatings and will conduct tests on them in the waters near Seattle.  In the next few years I will be able to report back on those coatings which I find provide the best protection for your boat here in the Puget Sound and are appropriate to how your boat operates.  It is a long time to wait but it is important to simulate a full two years of marine growth inside of a marina in shaded and sunny areas both.  I look forward to the results!

Happy boating to everyone!


Buying a high and dry boat

I did a survey recently on a boat which has sat out of the water on stands for about 8 years.  The engine was, for the most part, properly stored and this post is not really about the mechanical side of boat storage anyway.  What I want to discuss is the hull.  This boat was foam cored fiberglass and was of somewhat light construction.  The yard had also not taken measures to match the stands to any sort of underlying frame or bulkhead material where the boat is more stiff.  As a result, the boat was observed with intense distortion of the hull right at the boat stands.  I measured approximately 1.7 inch inward distortion and this was observed on the inside of the hull as well.  The prop shaft was also well out of alignment and very stiff to turn by hand.  Unfortunately this specific survey did not go far enough for me to get the opportunity to do some detailed inspection beneath where the boat stands were in contact with the boat but in my experience there are a wide array of possible outcomes for this from needing major work to there being no issues.

In all cases the boat should be put back into the water well before use, from a week to even a month.  This allows the boat to rebound back to its original shape as much as it is going to and as the hull shifts back into a final shape then the propeller shaft can be brought back into alignment if need be.  A foam cored boat might sustain some damage to the core material as was likely the case with the recent survey and this might require massive and expensive work to restore.  For some solid fiberglass boats it might not be as big of a deal to sit on land for such a long time but some distortion of the hull is expected.  Do be aware of the issue and if you know the boat has been out of the water for an extended time then make sure your surveyor knows too.  The surveyor will already be doing a detailed inspection of the effected area to determine what is needed to make the boat safe for you and your family but we also like any extra info that we can get about the boat’s past.  Any information helps us to better represent your interests.

Happy boating!


Shore Power Cord Fire

Shore power provides the all important trickle of electricity which keeps our batteries healthy, our bilge pumps with unlimited power in the case of a leak and energy to enjoy our boats at the dock.  While shore power is a beautiful thing the cord is one of many important items that requires inspection from time to time.  Corrosion on the contacts, those pieces of metal which transmit the energy, creates resistance.  Over time that extra resistance will create more and more heat until the plastic casing begins to break down and even burn.


The beginnings of a fire caught just in time.

The shore power connector shown above was replaced after it became evident that heat was beginning to build up due to corrosion on the contacts.  The owner noticed the issue mainly because their inverter/charger unit constantly monitors all incoming shore power to insure that the electricity is the right voltage, frequency and polarity.  While onboard the owner noticed that the inverter unit shut down the incoming AC power feed.  Inspection revealed that it only did this because the tiny smoldering fire inside the connector had done enough damage to make the incoming power feed unstable such that the inverter rejected the feed as being substandard.  It should be noted that most boats do not have a system that monitors incoming power and shore power cord corrosion often results a much more dramatic situation.  It is also important to note that this corrosion results in a persistent brown out and your onboard AC electronics will last much longer if you give them “clean” power.  So be sure to periodically inspect your connectors and repair or replace them as needed.  Your boat and budget will thank you!!!

Happy boating all!!!