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Bill H

So you want to build/buy a boat in the PH, here is the place to discuss it!

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Bill H

 

 

I'm a big fan of the Core Sound 17.

 

Now those are very pretty boats and yes, stitch and glue is a good method for small boats and popular.  Dudley Dix a Naval Architect of some note is also a big fan of stitch and glue.  They can be good boats and they are easy and quick to build.

 

I'm going to build a 16'ish tender for my 15m cutter.  I'll build her in aluminum because she'll see hard use and sport a 25ish HP outboard.  For just a knock about boat, the stitch and glue would be just fine here.

 

Nothing is finer than a good rowing dink.  I had one when I lived onboard in Texas.  Some of my best memories are of rowing that dink to the local restaurant for breakfast.  My very first boat was a row boat and I've always enjoyed rowing and paddling.

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Bill H

Using a used diesel engine from a truck to power your boat


 


 


It's the Pinoy way and it works more or less.  It's not without some problems though.  The big difference between a marine diesel engine and a truck diesel engine is how the engine is cooled.  The truck engine uses a radiator mounted in front of the engine in the front of the truck and air being forced through the radiator cools the liquid coolant that is circulating through the engine.  The two major factors to this idea that you don't have in boats is massive volumes of air being forced through the radiator to cool the liquid cooling agent.  Usually, you don't have a radiator because mounting a radiator down in the bottom of the hull where there is little air circulating is rather pointless.


 


The solution?  It's called a keel cooler and in its simplest form it amounts to a steel pipe or pipes which are affixed to the exterior of the hull below the water line.  The engine's water pump circulates the coolant through the pipes, thereby cooling the liquid coolant as it is returned to a reservoir to be recirculated through the engine.  If a person were to use copper pipes instead of steel the system would be much more efficient and copper is very resilient to most marine organisms so the pipes would not require cleaning nearly so often.  In short it works.


 


Interestingly, if you go to Europe or North America they will give you a whole list of reasons why the above will not work, yet it seems to work pretty well here.  It is true that a marine diesel has a larger oil pan which usually holds an additional gallon of oil but the lack of that larger oil pan doesn't seem to bother the used truck engines here.  Maybe they just speak Visayan so they never got the message printed in English.


 


Another unique feature to Pinoy propulsion systems is the truck transmission which is typically left attached to the engine.  The clutch is rigged and the operator can then shift gears.  It seemed funny to me at first, but it works...more  or less.  The traditional marine diesel has what is called a reduction gear which includes a reverse gear.  No manual clutch here, it is all built into the gear and shifts very smoothly.  Typically the reduction gear is in the 2:1 neighborhood.  Meaning for every two revolutions of the engine the propeller shaft turns one time.  Propellers in non-planing boats do not like high RPM's slower is always better in these circumstances.


 


​One thing typically not done here that I would do is to have the engine to be installed in the boat sent to a rebuild shop and have it thoroughly rebuilt.   Call me scaredy cat I guess, but I want an engine I can rely on and this would be the best way of getting one except buying new.


 


In the system I described above you still have to deal with the engines exhaust gases.  The traditional marine diesel frequently utilizes a heat exchanger which first cools the engine and then has the outflow of hot water injected into the exhaust thereby cooling it as well.  Then the combination of hot water and diesel exhaust is expelled out the back of the boat.  As an added benefit, the water also reduces the ambient sound level of the engines exhaust.  However, most mechanics today frown on this system because it adds a lot of complexity to the system and expense (heat exchangers are very pricey).  Most of all it is typically the root cause for many problems in the diesel engine.  The better system is a dry exhaust, which requires a muffler and the exhaust pipe to be wrapped in fiberglass so it does not get so hot it catches things on fire.  Fires on boats are very bad indeed and should be avoided at all costs.  The Pinoy used diesel installation utilizes a dry exhaust, which may account for some of the systems enhanced reliability.


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bluecarabao

Thank you Jon, we will have to agree to disagree when it comes to all things Arex.  Please keep in mind these folks are trying to sell you their product, so of course they will put it in the best light.  That said, if I were going to build a all out racing boat, epoxy and foam would be my first choice.  Remember the racing boat leaving Hawaii a few years back who had the misfortune of running into a sleeping whale, thereby pissing off the whale in the extreme?  The whale rammed the sail boat amidships and stove in the entire side of the boat sinking it.  The whale swam off leaving the crew to survive in a the boat's lifeboat until they could be rescued.  I'd like to think the whale got a goodly headache from that incident, but maybe he didn't, we will never know.

 

I would really like to see someone build some 20-30ish meter mono hull fishing boats here out of ferrocememnt.  I think they would certainly open some eyes to a different way of doing things.  My first concern would be getting the proper sand.  You need good washed silicon sand for the job but here in Mindanao and on Cebu most of the sand I've seen is naught but limestone, which would be a bad choice.

Here is an interesting boat made out of ferrocement  https://pdxccentric.wordpress.com/d2-sauvie-islands-ufo/

 

If i where ever to build a boat out of ferrocement,i would use basalt mesh instead of galvanized or SS mess. Basalt is stronger than steel,lighter than steel and will not corode/rust. One could add basalt fiber to the cement to make it that much stronger.  I kinda like that UFO boat design,lol.

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Bill H

Here is an interesting boat made out of ferrocement  https://pdxccentric.wordpress.com/d2-sauvie-islands-ufo/

 

If i where ever to build a boat out of ferrocement,i would use basalt mesh instead of galvanized or SS mess. Basalt is stronger than steel,lighter than steel and will not corode/rust. One could add basalt fiber to the cement to make it that much stronger.  I kinda like that UFO boat design,lol.

 

I'm not familiar with Basalt mesh and I don't claim to be an expert on all things Ferrocement, but it seems to me this mesh is very fine so my first concern would be ones ability to get the mud through the mesh so it was fully encapsulated.  I will do some more reading on it, thanks for the tip.  Do you have any idea how the cost compares to birdwire and steel?

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AussieLex

My last yacht was a ferro, 42 feet over all and weight about 20 tons fully loaded with fuel, water etc... I had it powered with a Perkins 4/236 diesel, 85 HP .. and a Borg Warner Velvet Drive gearbox 1:1 ratio, 20 inch prop not sure of the pitch ... at 1500 rpm, cruise speed was about 6.8 knots. That was the economical revs, the sweet spot really although she would run out to about 1850 rpm if pushed.   The boat was a Robert Tucker design and professionally built in the UK in the early 90's and you couldn't want a tougher boat believe me. I grounded her several times  and when I slipped her she showed no signs of damage or fatigue... 

 

 

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Bill H

I contacted the company who is selling/promoting the Basalt products and told them what I wanted to do with it and asked for advice and pricing info.  We'll see how they respond.

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Oz Jon

I had a Toyota 2c 4-cyl diesel on my 43ft cat - a used engine (imported by the container load to Aus from Japan - cost A$500 in 2000). [i understand they were ex Japanese Lite-Ace vans]

A very nice engine. Nominally about 70HP at crazy high revs, but I never exceeded 2-3000 RPM (I guess 40-50HP). Would push my boat along nicely at 5-10kts.

 

I fitted a hydraulic gear pump which drove 2 similar sized hydraulic gear motors (1 in each hull) via a twin (fwd.neutral.rev) hydraulic valve. That resulted in a 2:1 rev reduction to the props. 30gals/min oil flow at 3000psi at my 60Hp design power. (I never exceeded 2000psi in practice). - very efficient!

 

Cooling was DIY - 60ft of 1/2 copper tube in three 4'' coils carrying seawater, fitted inside a length of 6" copper tube, ends capped and filled with coolant - mounted in the engine compartment - 2 more coils in the hydraulic reservoir tank - it worked well!

A bit of lagging and Al-foil around the exhaust manifold (to reduce the engine compartment air temperature) and all cooling seawater injected into the exhaust. Belt driven 3/4" seawater pump at about 3/4 engine revs.

 

The only reason I replaced that engine, 10 years later, was that it developed a coolant pump seal leak. (a $20 fix without labour)

However getting it off the motor was an access nightmare! - I gave up # (and got another similar motor) after breaking a cast metal timing pulley trying to get that off to gain access to the pump!

 

# there comes a time when dogged perseverance turns into obstinacy! - and life is too short! - Lol!

Edited by Oz Jon
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Bill H

 

 

# there comes a time when dogged perseverance turns into obstinacy! - and life is too short!

 

Sometimes it feels like if there were a God, he'd introduce us to the fools who design engines with parts you just can't get to in order to replace them!  Then he'd let us have our way with them for five minutes or so and insure we were not liable for the hospital bill.  LOL

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Bill H

You don't see much hydraulic power on boats.  In an application like your Cat it makes some sense, but you still have significant heat issues to deal with and the over all efficiency of such a system is not very good so the market gravitates toward the more fuel efficient systems.  All of the above is why I'm gravitating towards diesel electric power systems.

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Oz Jon

you still have significant heat issues to deal with and the over all efficiency of such a system is not very good so the market gravitates toward the more fuel efficient systems.

When I looked into propulsion solutions for my boat, at first I came to that conclusion too, based on observation of hydraulic driven boats and other sailor's reports. Very few were happy with what they had.

 

However, looking deeper into why, I found the reason.

 

Almost universally they were using swash-plate (or similar variable speed/reversable pumps/motors to avoid the need/cost of rather expensive incremental hydraulic valves).

That type of pump/motor is quite efficient only over a very narrow speed range, but spend much of their operating time outside that range, at low (even very low) efficiency.

 

The key to the success of my design is the use of gear pumps and gear motors. They have efficiencies better than 80% over a very wide rev range, independent of running direction.

 

I always intended to actually measure the overall efficiency (by calorimetry on the hydraulic oil cooling) but never got around to it. However, I know that the system was efficient because the hydraulic oil cooling water dribbling out via a 1/8" fitting was at most, tepid. Any inefficiency should show up in that cooling water.

Not very scientific, but a good indicator.

 

A mechanical gear box of course is more efficient than any hydraulic system, but not by much with good design, and other factors ( particularly for a cat) clinched my decision. One engine plus all the hydraulics was about 1/4 the cost of a pair of engines and gear boxes and CV (or similar) drive shafts..

 

Anyway - I'm an Engineer! - I like the challenge of coming up with good, unusual solutions! - Lol!  [see my avatar text!]

 

ps. Yes times have changed! - If I were to start again, I'd look seriously at diesel electrics - there is now some good stuff around these days and very good control and installation location options.

Edited by Oz Jon

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richard_ost

I personally don't see a point using hydraulic motors as a propulsion system, unless you really have no space at the aft or you want to have some sort of pod-propulsion (with pods I would go with electric motors though). But on the other hand you generally don't have any space in any boats. And still you can 99% of cases fit an inboard or sterndrive propulsion system there, because you have to.

 

With the average Filipino pumpboats (1000kg) a few kW-electric engine would be enough giving you the speed of 5-10kn, you can easily fit a 1-2kW solar panel system there with batteries. And if you want to cruise for longer periods you can use a light gasoline generator that you can always carry on and out of the boat http://powerequipment.honda.com/generators/models/eu2000i

 

Here's a calculation for an example boat (narrow hull, catamaran):

lenght LWL                            7m (23')

load mLDC                         1 000kg (2 222lb)

 

speed V5                      5kn

power P5                      1kW (1,3hp)

 

speed V7,5                   7,5kn

power P7,5                   3,5kW (4,8hp)

 

speed V10                    10kn

power P10                     6kW (8hp)

 

With a pumpboat (trimaran) the drag would be slightly less.

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richard_ost

I personally don't see a point using hydraulic motors as a propulsion system, unless you really have no space at the aft or you want to have some sort of pod-propulsion (with pods I would go with electric motors though). But on the other hand you generally don't have any space in any boats. And still you can 99% of cases fit an inboard or sterndrive propulsion system there, because you have to.

 

With the average Filipino pumpboats (1000kg) a few kW-electric engine would be enough giving you the speed of 5-10kn, you can easily fit a 1-2kW solar panel system there with batteries. And if you want to cruise for longer periods you can use a light gasoline generator that you can always carry on and out of the boat http://powerequipment.honda.com/generators/models/eu2000i

 

Here's a calculation for an example boat (narrow hull, catamaran):

lenght LWL                            7m (23')

load mLDC                         1 000kg (2 222lb)

 

speed V5                      5kn

power P5                      1kW (1,3hp)

 

speed V7,5                   7,5kn

power P7,5                   3,5kW (4,8hp)

 

speed V10                    10kn

power P10                     6kW (8hp)

 

With a pumpboat (trimaran) the drag would be slightly less.

 

Just realized those powers are calculated when efficiency of the propulsion system is 100%. More like 40-50% is accurate after you lose power in the motor and propeller, so multiply all the powers by 2 and you get the amount of power you have to install on your boat.

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Bill H

I personally don't see a point using hydraulic motors as a propulsion system, unless you really have no space at the aft or you want to have some sort of pod-propulsion (with pods I would go with electric motors though). But on the other hand you generally don't have any space in any boats. And still you can 99% of cases fit an inboard or sterndrive propulsion system there, because you have to.

 

With the average Filipino pumpboats (1000kg) a few kW-electric engine would be enough giving you the speed of 5-10kn, you can easily fit a 1-2kW solar panel system there with batteries. And if you want to cruise for longer periods you can use a light gasoline generator that you can always carry on and out of the boat http://powerequipment.honda.com/generators/models/eu2000i

 

Here's a calculation for an example boat (narrow hull, catamaran):

lenght LWL                            7m (23')

load mLDC                         1 000kg (2 222lb)

 

speed V5                      5kn

power P5                      1kW (1,3hp)

 

speed V7,5                   7,5kn

power P7,5                   3,5kW (4,8hp)

 

speed V10                    10kn

power P10                     6kW (8hp)

 

With a pumpboat (trimaran) the drag would be slightly less.

 

Well you're right of course, except when it comes to powering cruising Cats you don't have very many choices.  You can mount an engine in each hull, which has good and bad points.  Yes, it gives you the ultimate redundancy, but it also gives you two expensive motors to buy and maintain, etc.  The redundancy is kind of a fallacy as well since diesel engines are extraordinarily reliable and when they do have a problem, more often than not its a fuel problem.  Running two engines off a common fuel supply means when bad fuel is the culprit, both engines are lost.

 

Hydraulic power saves weight, is simple to operate and maintain and when considering the cost of two diesels fairly cost effective.  It never really caught on for all the reasons Jon  outlined in his excellent article on the subject one page back.  That said, I think the growing alternative today is diesel electric propulsion, but that's just me.

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AussieLex

Most catamarans run 2 separate fuel tanks ... keeping the weight balanced by placing tanks down low in each hull ... the smart guys have 2 main tanks and 2 smaller day tanks they transfer the fuel into for immediate use... I also ran a water trap and two filters in line for each engine ...

 

You have some good ideas for sure but in places i disagree but mostly thats because of personal preference  ... the old saying is true...put 4 sailors at the bar and ask one marine question and you are sure to get 6 different answers... smiles... great thread ..

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Bill H

An Update on Basalt Products

 

 

I've had an interesting exchange of emails with the Basalt Products folks.  Nice people those.  The short version of the story is yes, these products offer many of the advantages of steel at half the weight (at the same strength).  They suggest sticking with concrete however, in lieu of going with epoxy to replace the concrete.  This because the epoxy while perhaps stronger is also much more brittle, so it would not afford very good impact resistance.

 

To me, the downside of the product is cost.  It is roughly double the cost of the equivalent steel products.  However, as the products are stronger than steel, you could go with smaller dimensions thereby saving some money without sacrificing strength.  They claim the concrete adheres to the basalt better than steel as well and of course no rust problems and especially no conductivity issues of the product is a very good thing where boats are concerned.

 

My one unanswered question has to do with flammability.  Is the basalt flammable?  I did not ask them this question until this morning, so I expect to hear the answer in a few hours.  I'll keep you posted.

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