mixman why the trawler?

I really like CATS and have been drawn to their design and parameters for many years. Probably one of only a few hundred folks that collected all of the earlier "Multihull" magazines until they went out of business. Between the mags and a few books on hull design I was intrigued by the prismatic coefficient effect with water performance of their hulls. Although I have only owned a couple of smaller CATS I was able to get on a bunch of CATS above 40' in length at various boat shows and even out here at Block Island. (Benchmark, Endeavor, Transcat.
If you view the Cats silhouettes it is fairly easy to see that the volume inside if a typical monohull far exceeds that of a catamaran design. Going on board confirms this as tankage, engine spaces and usually staterooms feel the pinch.
And that is where some of this statement comes from - "But the Gulfstar "Trawler" does have a heck of a lot more living space. A LOT MORE LIVING SPACE!"

Good luck with your project and refit plans - happy boating
 
The Gulfstar is 36' by 12' beam. Our cat is 30x9'6". The Gulfstar is physically quite a bit larger. Personally I've always found catamarans to have larger living space and a much better ride in various sea conditions. I will, however, completely agree with you that some access is limited. I really wanted an Endeavour 36 or a PDQ 34 but I wasn't crazy about the engine access in either one. An inboard diesel crammed into the port end of each sponson doesn't sound like fun to work on or check on!
 
Owning a small business for over 21 years I think I know a thing or two about doing business. So now I'm going to comment on marine businesses; they suck! I've had 2 "supposed" refit companies look at this boat and one just turned down my business and the other refuses to give me a price estimate. Really, morons? Everything I want to be done I can do myself but I'd rather pay to have it done at this point in my life as I'm still working and I've got the money. I'm giving both companies a couple of weeks to get their crap together and then they're both going to get Active Captain reviews from me.
 
That's bad news. More and more, labor intensive business is refusing to provide quotes so they can hold you hostage. For example, I asked to find the source of an issue in one of our engines. Every Detroit shop I have been to has said "you need kits", or we'll drop the oil pan (set up for a kit job) and within a day we'll tell you what the problem is.
Speaking with mechanics that have moved on from the big shops, they give me the scoop, and the test is very simple by pulling the airbox covers off the 6-71 and taking a peek at the piston crowns.
Back on point, when asked about a "kit job" the response is time and materials. No caps.

We get that from plumbers working at the association as well.
 
I don't know, I think a lot of people in the marine business are tired of getting burned on giving estimates.

Till you open many things up there is no way to give a realistic estimate many times. And the times when you give an estimate with the warning the owner that the price could go up quickly based on what you find after you start the job, people suddenly forget you ever said that once the bills start coming in.

I've seen companies give an "estimate" just to get the work knowing the bill will go up once they start the job and have the owner on the hook.

Sometimes it's more honest and realistic not to give a hard estimate.
 
I primarily do two things at my office. One is bookkeeping, which is boring as heck but very much necessary. The other thing I do is provide estimates. Without an estimate there is no contract. Without a contract the customer and the vendor are most likely screwed. I think there are way too many people in the marine industry that have no clue how to conduct business.
 
Kurt,
Good luck with your trawler.
I looked at a used 36 Gulfstar years ago but decided to purchase a 34' new 1979 Marine Trader instead.
http://www.boatus.com/boatreviews/power/marinetrader342.asp
We loved our Trawler, with two boys and two staterooms, we spent every summer weekend on it, often anchored out overnight to avoid the long trek back to the Marina.
On two particular occasions I felt challenged due to the low 120 HP single engine.
One time while entering a very rough NJ inlet I had to work hard to keep the bow headed in. Rollers seemed to want to catch the stern and swing the boat around.
On another occasion while running the Point Pleasant canal under the old bridge found that the opposing current was so strong that I barely inched under the bridge at full throttle. Really scary!
Had I known better, I would have waited for the current to become slack. Now I know that why all the sailboats were waiting at anchor at the head of the canal, they would not have been able to beat the current.
I used to burn about 110 gallons of diesel per year running about 100 hours, and typically ran about 7 knots in the bay. If one ran the engines at higher RPM, the boat did not go much faster, just made more wake and lowered the stern.
It took us 12 hours to run from Barnegat inlet to Fire Island inlet on a nice day on a calm Ocean.
Ultimately we wanted travel a little more and bought a faster 40 footer with twin 454's.
No egrets with either boat.
 
The "trawler" for us is the retirement/cruising boat. We've got the 30' power cat for use before we retire (and will keep her in storage for while after we retire). The catamaran has taken us from the "top" to the "bottom" of the Chesapeake many times for the last decade we've owned her. Via trailer to Florida she's also taken us to the Abacos/Bahamas 4 times and the FL Keys twice. Now we're looking for a semi-liveaboard for longer cruising when we "early-out" in a couple of years. We won't be in a hurry so comfort is the main motivation.
 
And smaller engines will reward you with some economy. We took the other side of the trade off where we have larger engines in case we needed to run. We have only used them once, when surrounded by spouts in the middle of the Gulf Stream. Occasionally I have been happy when surfing along in following seas, but we could have avoided most of those circumstances.
A little skill and judicious application of reserve throttle will often resolve any of the issues we encountered. 150 hp 4 strokes would probably work just fine in Freedom even though she has 400 HP detroits.
 
I'll never see anything over 7 knots (unless going "downhill") but the full burn is reported to be about 2gph.
 
smaller engines don't give more economy. It takes X power to move a boat and diesels produce a fairly flat 18-20 hP per gallon of fuel per hour.

Big engines run slow or small engines run hard will do about the same.
 
Agreed. But the smaller engines are a heck of a lot easier to maintain if they are simple. Smaller turbos, trannies, shafts, props, oil changes, filters, name it. They are cheaper to run and maintain.
 
Turbos? Ain't no stinkin' turbos on these old Perkins! :-)
 
My Ford Lehman 6 cylinder diesel had 120 Hp with 380 cubic inches.
Did not work too hard at 7 knots, boat seemed to dig a hole when I pushed the throttles to full, don't think it went more than 8.5 knots but surely made a lot more noise on the 34' Marine trader, which slipped through the water with little energy at lower speeds. I noticed that when entering the slip and taking it out of gear the boat seemed to coast a good distance, had to put in reverse to break momentum at slip. When I got a planning hull with twin 454's the new boat almost stopped instantaneously when taken out of gear.
The Ford engine was a British commercial engine that was imported Marinized by Lehman in Linden NJ.
 
"smaller engines don't give more economy. It takes X power to move a boat and diesels produce a fairly flat 18-20 hP per gallon of fuel per hour."

I agree with you Bruce - On most all 'modern' 4 stroke diesels that number range is pretty much it but the early Perkins we had did not get quiet those hp numbers per gallon of fuel. We had two trawlers both with diesels one a single and one a twin both with Perkins diesels. Nice engines and good for cruising but I never was totally happy with the rotary injection pumps of the price of the 'smaller' replacement parts. Those engine will not see 18 hp per gallon , you will be about 15% below that number.

"We took the other side of the trade off where we have larger engines in case we needed to run."
"Agreed. But the smaller engines are a heck of a lot easier to maintain if they are simple. Smaller turbos, trannies, shafts, props, oil changes, filters, name it. They are cheaper to run and maintain."

And I agree with you as well Dan - We ended up with two 'smaller' 6 cylinder inline 4 stroke diesels that have not cost all that much to maintain or run but still can give some nice cruising economy at both hull speed and on plane. The ability to go faster can really help you play the tides at times or work a weather window.
But all boats are a compromise so its best to choose wisely as the initial acquisition costs are rarely the biggest part of the picture.
Hope this helps
 
true and the old two strokes didn't do as well on fuel either. So it can make a difference if you have modern engines or not but given the same class of engine the fuel used to move the boat is not really related to engine size.
 
True Bruce - and most folks are not aware that any diesel has a large variation in the Hp / gallon across its own hp and rpm range. If you think about it why would anyone know all this crap anyway? It is never part of a spec sheet or discussion when boats are sold as the marketing folks do not want to cover it anyway. Most all 4 stroke diesels have a fairly significant variance in the hp produced per weight of fuel over their recommended rpms - typically 25-35%.
So operating the engines within their 'sweet' spot will yield more hp per gallon and hence better mpg for that exact speed. Problem is that many of us do not want to travel at the engines best rpm (or the boat hulls best Speed) so a lot of the talk about best mpg or gph ends up being just talk. Somewhere around here I have the old spec sheets on these Perkins 4-108 engines that were in my trawler and I believe that they had a variance across rpm's of about 35% and a fuel use average of about 0.5#'s per hp per hour.
Not bad for the age of those engines and the way they just run all the time.

Hope this helps
 
You don't often see BSFC curves but part of the reason is they don't really relate to the prop demand curve power level. I guess you would need a family of BSFC curves to see where they intersect with the prop curve at the intended operating point. But none of this matters much as the prop curve is just another guess. As much as the "trawler" types obsess over fuel use they don't understand much
 
quote:
Originally posted by smitty477

Somewhere around here I have the old spec sheets on these Perkins 4-108 engines that were in my trawler and I believe that they had a variance across rpm's of about 35% and a fuel use average of about 0.5#'s per hp per hour.

Click to expand...


Those are the engines I have in my Gulfstar. If you can find those spec sheets I'd sure be interested in seeing them!

Aren't there a lot of factors that go into fuel/rpm/economy? With my power cat I've got NMEA2000 info from my Honda outboards to look at and I can max out fuel economy depending on conditions easily. But it is a semi-displacement hull and a catamaran so things are crazy different from mono-hulls. I find that 5,100 RPM with twin 60hp outboard runs the boat around 17-18 knots and burns about 7.5 gph. That seems to be the sweet spot for this configuration. Yet my Gulfstar is only 6' longer and only has 4hp less but will never, EVER get on plane since it is full-displacement.
 
Kurt:
That variation across RPM range, BSFC, is at max hp, the max hp curve. Unfortunately that curve is very different than the actual load on the engine that is determined by the propeller and approximated by the prop curve. The BSFC curve does not tell us anything about BSFC at less than max hp at each RPM.
If you look at a chart of both curves you will see that they differ greatly except at the max rated point, if and only if the boat is propped properly.
 
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