| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 519.1 | pass everything but the gas pump | SMURF::AMATO | Joe Amato | Wed Sep 20 1989 12:46 | 8 |
| Unfortunately, with that boat I'm not sure how much you'll be able to
economize. Thats a relatively heavy (11000lbs I think) boat, and a deep
V to boot. Most of the people with Bertram 28's that I've spoken to
have given figures around 1mpg. They would run aruond 20kts and burn
about 20gph. The flow meter will help, as will keeping the engines in
tune. Another thought might be an engine synchronizer. The best thing
is to go easy on the gas, and run them at the lowest rpm that'll keep her
on plane.
|
| 519.2 | How much do flow meters cost anyway ? | ULTRA::BURGESS | | Wed Sep 20 1989 13:41 | 13 |
|
Something I've never thought about before is the miles per
gallon, I only think in gallons per hour. If someone is really interested
in only the scenery while getting there I would have to guess that trolling
on one engine at idle speed would consume the least fuel PER MILE.
Or, don't open up the secondaries, a fuel flow meter will help
determine the throttle position where they open.
Or, get rid of the 4bbls
R
|
| 519.3 | Tried Tabs ? | HPSTEK::HOBBS | | Wed Sep 20 1989 20:06 | 23 |
| Very interest question. I've been spending a lot of time in an
airplane seat lately, which has presented an opportunity to catch up on my
reading. Boating magazines normally have a number of boat evaluations in
each issue. Each evaluation usually contains the information, in the form
of graphs, showing plots of GPH/RPM, RPM/Speed, and MPG/RPM etc. I believe
the answers to your questions may exist in the library. You don't say if
your Bertram is new or older. I think I will be looking for the same info
for my boat (34 Silverton) this winter.
My question has to do with trim tabs. Do all boats benefit from
Tabs ? Probably so, but to what extent and what's the pay back? The boat
next to me in the marina is almost identical to mine with a couple of
exceptions: Chryslers vs Crusaders, and I have Tabs and Jim doesn't. The
last couple of times we have gone out together we have been comparing speed
by LORAN, RPM, and no Tabs vs Tab down. So far results look like:
No Tab Tab down
RPM 2800 2800
Speed 10.3 14.2
Seems from this one data point that Tabs have a considerable
impact. Anyone have any more data ?
Rick
|
| 519.4 | Sounds familiar! | HSKAPL::LUPANDER | Jan-Christian Lupander | Thu Sep 21 1989 02:41 | 23 |
| Your concerns and priorities sound very familiar!
I have looked into these issues (note 513) and altough the technical
sides are very different (twin 4-stroke inboard vs single 2-stroke
outboard) some general conclusions can probably be drawn:
- there is a fairly well defined economic speed range outside which
consumption will increase steeply. (Might be accentuated with a
2-stroke).
- running at 60..80% of max power rpm will put you in the right
region. (Might be different for 4-strokes)
- prop choice is important when chasing the last mpgs.
- without proper instruments (with proper calibration!) determining
absolute economy is very difficult.
- good flowmeters are expensive but serve the additional purpose of "all
ok" monitors after they have done the initial job of providing
data for the basic boat/motor characteristics.
- trimtabs as such are very beneficial for a number of reasons but
do not necessarily improve economy at normal cruising speeds.
Again testing is the only way to really find out!
-jcl
|
| 519.5 | Flow Metering? | SSVAX2::REDFIELD | | Thu Sep 21 1989 14:53 | 19 |
| On the subject of flow meters...
.4 refers to "good ones". Anyone have any data regarding the good and bad
ones, tradeoffs etc.? I am seriously thinking this might be the way to go.
Various experiments on the water have given me a range of fuel consumption
that varies between 15 and 24 gallons per hour. This is without going into
a 4 barrel mode. The issue I have is not being able to reproduce the
performance. It is not just RPM related. There are other variables at
work that are altering the load thereby causing different fuel consumption.
It seems to me that knowing gallons/hour by engine can provide the
simplest set of metrics to operate optimally. I once rented a car that had
this type of fuel gauge. It not only provided instantaneous miles/gallon,
it had average mi/g,gallons left, gallons used,estimated range remaining.
I found that for the two weeks I had the car, I drove differently.
With a 30-40% potential difference in fuel economy certainly can justify a
lot of effort.
|
| 519.6 | | WEDOIT::JOYCE | | Thu Sep 21 1989 15:08 | 5 |
| Just about every boat report I have every read with an I/O or Inboard,
the best fuel consumption was while running around 3000 rpm. So
you can pay a few hundred bucks for a fuel flow meter or try running
the boat around 3000 rpm and set some type of baseline and compare
other speeds to it.
|
| 519.7 | 2 QUESTIONS | TIS::GRUHN | | Mon Sep 25 1989 13:27 | 31 |
| This reply could be titled "Boating On A Wornout Shoestring" This
summer I got my boat back in the water after about 6 years of sitting
in the back yard. I have an old 14' fiberglass runabout made by a
company called Duo from Decatur, Indiana in 1963. When I got it it was
powered by a 20 horse Johnson. Worked well for quite a while till it
got done in by a severe storm those 6 years ago. Having children to
educate and another house to buy said no spare money for boats. Last
year I got hold of a 1958 35 hp Johnson that turned out to be a fresh
water motor with very few miles on it that someone had been using for
a parts motor. Was able to come up with all the needed stuff to put
it back in order and this year was able to complete the work on the
damaged hull. The results are great and once again am enjoying
fishing, clamming and general pleasure boating on Barnstable Harbor.
The boat doesn't leak and the motor runs beautifuly. What's the
problem? Fuel consumption. I can't realy remember how much gas the
old 20 used but the older 35 seems to be quite a bit thirstier. Does
anyone out there remember how much fuel these old motors use? The
prop is a pretty standard looking three bladed thing.
Next season I will be able to take some figures and be able to ask
"Is this motor burning too much fuel?". In the interim I am only
asking what sort of fuel consumption this motor should have.
Also on another topic but the same boat, has anyone had any exper-
ience filling the space between the hull and the deck with foam-in-
place insulation and what are the merits or lack of merit to doing
this?
Bill
|
| 519.8 | floatation | TYCOBB::J_BORZUMATO | | Mon Sep 25 1989 16:03 | 23 |
| On the fuel consumption, "whats a lot" seems the most common
denominator is gals. per hr. the vintage you talk about was
made a a time when gas was relatively inexpensive. But anyway
if no one made any changes, you have a point ignition system
and have none of the benefits of the more modern engines.
I'm sure of one thig weight is certainly a consideration.
But i'm not an expert on outboards, i'm sure that one of our
"motor head" advisors will reply
On the floatation not "insulation" without the flotation if
you take on enough water the boat will sink. No issue here.
With the flotation the boat might only get swamped, or fill and
float at the gunnel level. I've seen advertisements for the flotation
you are in question of, the manufacturer shluld be able to give
you the metrics for youdr boat. I'm sure Boat U.S. can help
you find what you need.
keep your head above water....
jim..
|
| 519.9 | a couple or three GPH on a 35 HP Johnson ??? | ULTRA::BURGESS | | Mon Sep 25 1989 17:00 | 26 |
| re .7 My totally subjective impression {sufficient
disclaimer yet ?} is that the 35 horse Johnson I rebuilt this summer
uses almost a six gallon tank full in about 3 hours, maybe it only
lasts a couple of hours if there's a skier. Bottom line is its not
expensive, just a hassle having to drive to town to get gas for every
day the boat is used for a few hours.
re figuring it theoretically; the carb's cfm determines how
much fuel an engine "could" inhale. How much it actually "does" inhale
is determined by how well the engine sucks on the carb and how long it
is kept at max throttle opening.
re my next boat (based partly on some questionable
assumptions, but mostly on mere dreams) will have an hour meter. I
shall record the number of gallons and the hour meter reading every
time I fill it, I will run a spread sheet similar to the one I use to
figure MPG on my car (must remember to put the gallons on the top and
the hours on the bottom of the fraction this time....(-: ) At a
guess it will consume about 5 or 6 gallons per hour, which I regard as
affordable entertainment at current fuel prices. Other costs will
dominate; like sales and excise tax, insurance and depreciation,
eating out on the way home, etc.
R
|
| 519.10 | Duo's... I thought I was the only one who had one 8^) | AITG::KARR | | Tue Sep 26 1989 10:20 | 24 |
| re.7 >
Bill,
I have 2 boats (I bought a new boat this year) and one of them is a
16' duo. (1964) vintage... It is powered with a 1965 evinrude
sport four. (60 hp) I don't have any input on fuel economy but will
say that my 60hp evinrude is burning 6 gallons in about 2.5 hours
under full skiing conditions.
I am more interested in finding out what you had to do to the hull.
My DUO is now up for sale.. boat motor and trailer out the door for
$1000.00 or BRO. It has a slight hooked hull on the starboard side.
I suspect a weak stringer under the floor. Is this what your hull
problem was? I have also talked to fiber glass repair shops who have
indicated to me that it is a relativley easy job to fix. I am not going
to do it but am curious as to what you have done.
The hull is in ok shape and does not take on water. It does (obviously)
affect the performance of the boat but for what I bought it for,
teaching my 5 year old to ski and my wife the rules of the water way,
it was super! I have had the boat for 4 years. eagerly awaiting your
reply...
Roger_with_a_new_BAyliner.....8^)
|
| 519.11 | Duo Repairs | TIS::GRUHN | | Tue Sep 26 1989 11:01 | 21 |
| Hi Roger, maybe we should form a Duo owners club. Great little boat.
Some number of years ago I bought this old timer from a neighbor.
When I got it, it had a damaged transom. The fellow backed his trailer
with the boat into his back yard only the motor wasn't tilted up and
the griund was soft and the bottom of the motor cought in the dirt etc,
etc,etc. I fixed it up temporarily and used it for some time. What I
didn't realise was that the motor well drain tube was not sealing and
was saturating the wood of the transom with rain water and rotting at
a great rate. Then one fall when I was away on business the boat got
caught in a bad storm and driven up on the rocks. I got a couple of
holes in the hull and lost the motor. Replaced the motor with a 35
horse Johnson which I talk about in one of the other notes and this
summer had the time and inclination to repair the boat. I removed all
the wood from the transom and replaced it and repaired the holes in the
hull with fiberglass. No problems all told, but lots of work. The
hull is fine now. It isn't a hooker or a rocker so I can't offer
any help there.
Bill
|
| 519.12 | BERTRAM 28 FUEL ECONOMY | GERBIL::BOSELLI | | Tue Oct 03 1989 23:27 | 38 |
| THERE ARE TWO SCENARIOS IN WHICH TO MAXIMIZE YOUR FUEL ECONOMY----
#1 YOU'RE TAKING A 3 HOUR AFTERNOON CRUISE...IN WHICH CASE YOU'RE
CONCERNED WITH GALLONS PER HOUR.
#2 YOU'RE GOING FROM GLOUCESTER TO PROVINCETOWN AND BACK...IN
WHICH CASE YOU'RE CONCERNED WITH MILES PER GALLON.
THERE'S A BIG DIFFERENCE. IN THE FIRST CASE, THE SLOWER THE BETTER
IS THE GENERAL RULE OF THUMB (ASSUMPTION IS THAT YOU'RE NOT IN A
HURRY). IN THE SECOND CASE, IT BECOMES MORE OF AN ISSUE OF 'WHAT DOES
INCREMENTAL RPMs GIVE YOU IN INCREMENTAL MILES PER HOUR?'. IN THE SECOND
CASE, AS SOMEONE HAS ALREADY POINTED OUT, 3,000...MAYBE EVEN 3,200...RPM
ALMOST ALWAYS YIELDS OPTIMUM MILES PER GALLON. ON AN ABSOLUTE BASIS, IT
TAKES MORE GAS PER HOUR, BUT WHEN THE BOAT IS UP ON A COMFORTABLE PLANE,
IT'S SO MUCH EASIER TO PUSH THAT YOUR MILES PER GALLON IMPROVES.
ANOTHER RULE OF THUMB: 260 HP ENGINES (350 CUBIC INCH) SHOULD TAKE ABOUT
9.5-10 GALLONS PER HOUR AT 3,000 RPM. BERTRAM PUBLISHES THAT YOUR BOAT
BURNS 20.1 GALLONS/HOUR AT 3,000 RPM YIELDING 26.8 STATUTE MPH FOR 1.33
STATUTE MILES/GALLON (1.16 NAUTICAL MILES/GALLON). IT LOOKS FROM THE
BERTRAM CHARTS THAT I HAVE, THAT ANYTHING OVER 3,000 RPM...ON THE 28...
CAUSES MILES/GALLON TO DROP FAIRLY QUICKLY. SOMEWHAT SURPRISINGLY,
2,800 APPEARS TO BE OPTIMUM FOR YOUR BOAT (17.6 GPH YIELDING 24.2 MPH
FOR 1.38 MPG).
IN CASE YOU'RE INTERESTED...TOP SPEED IS 36.9 STATUTE MPH AT 4,200 RPM
BURNING 39 GALLONS/HOUR FOR 0.95 MPG.
ALSO INTERESTING TO NOTE THAT USING 230 HP ENGINES (305 CUBIC INCH),
THE MILEAGE FIGURES WERE JUST A LITTLE WORSE THAT WITH THE 260s.
THAT'S WHY BERTRAM SWITCHED TO 260s EXCLUSIVELY IN '83 OR '84.
CONCLUSION: THAT'S A LOTTA GAS...BUT THAT'S ALSO AN OUTSTANDING BOAT...
PROBABLY ONE OF THE LONGEST LIVED FIBERGLASS CLASSICS...
FIRST BUILT IN '72 AND STILL BEING SOLD TODAY - SAME HULL!!
Z
|
| 519.13 | Bertram Documentation | SSGVAX::REDFIELD | | Tue Oct 10 1989 15:26 | 28 |
| I appreciate the data. Sounds as if you are quoting some documentation
that you have. I would be very interested in a copy.
If you get the chance please mail to Carl Redfield
MLO 1-5/T33
Thanks,
Carl
>================================================================================
>Note 519.12 Fuel Economy - How to obtain? 12 of 12
>GERBIL::BOSELLI 38 lines 3-OCT-1989 22:27
>--------------------------------------------------------------------------------
> -< BERTRAM 28 FUEL ECONOMY >-
>
> ANOTHER RULE OF THUMB: 260 HP ENGINES (350 CUBIC INCH) SHOULD TAKE ABOUT
> 9.5-10 GALLONS PER HOUR AT 3,000 RPM. BERTRAM PUBLISHES THAT YOUR BOAT
> BURNS 20.1 GALLONS/HOUR AT 3,000 RPM YIELDING 26.8 STATUTE MPH FOR 1.33
> STATUTE MILES/GALLON (1.16 NAUTICAL MILES/GALLON). IT LOOKS FROM THE
> BERTRAM CHARTS THAT I HAVE, THAT ANYTHING OVER 3,000 RPM...ON THE 28...
> CAUSES MILES/GALLON TO DROP FAIRLY QUICKLY. SOMEWHAT SURPRISINGLY,
> 2,800 APPEARS TO BE OPTIMUM FOR YOUR BOAT (17.6 GPH YIELDING 24.2 MPH
> FOR 1.38 MPG).
>
> IN CASE YOU'RE INTERESTED...TOP SPEED IS 36.9 STATUTE MPH AT 4,200 RPM
> BURNING 39 GALLONS/HOUR FOR 0.95 MPG.
>
|
| 519.14 | TURBOS FOR FUEL ECONOMY | RIPPLE::ARROWSMIT_GA | | Thu Mar 08 1990 12:13 | 8 |
| A FREIND OF MINE HAD A 26 FOOT HAWIIAN STYLED BOAT WITH A 460 FORD ENGINE
BEING MORE INTERESTED IN GOING FASTER THAN 60 MPH OR SO HE INSTALLED
TWIN TURBOS. HE BLEW HIS HEAD GASKETS WHEN THE BOOST WAS SET TO
MAXIMUM WARP. ANYONE HAVE ANY EXPERIENCE WITH TRYING TO OBTAIN MORE
MPG FROM TURBO CHARGERS, FUEL INJECTION OR WATER INJECTION ON OTHER
THAN RACE BOATS?
|