Absolute Noob seeking advice and knowledge.

[racerone]

Plugs won't foul on these motors if in good condition!!!----Was down in the Paris area to assist a new boat owner the other day.-----Removed powerhead and lower unit for winter overhaul.----After I was done in the storage barn they said " thank you very much and have you considered teaching about outboards and boating "

 

[dwco5051]

Re the bolt, yes, too true!

thanks for the explanation on the tilt/trim. I was looking for a separate control.

Trim changes the angle of attack my raising the bow. The higher the bow the less wetted area of the hull and less drag due to the friction from the water. Trimmed all the way down will get you on plane faster and is called by boaters as the "hole shot" Think of it as a short field takeoff. When running in rough water you may want the bow down to smooth out the ride as the boat well be slicing through the water especially in a V hull. Most efficient speed for most boats is at a 100 or so rpms over what it takes just to keep the boat on plane. It won't take you long to figure out trim and speed at different loads and weight distributions. There are no weight and balance calculators for small boats so it is seat of your pants and experience.

 

[Scott Danforth]

The boat: 1985 Thundercraft Bowrider. 17’ 140 Johnson. Recently had all the flooring, and seats replaced.

This line scares me the most. the motor stuff is easy.

however the flooring being replaced is most likely a "deck over" where they simply slapped a new wood deck over the rotten floor, stringers, foam and transom.

fiberglass boats from the 80's are notoriously bad with their initial build quality and 99.5% of them have rot. the 0.5% of them that do not are most likely still locked in the garage or have undergone a restoration

If it was me, I would like to know what was replaced along with the floor.

 

[KodiakJack]

Plugs won't foul on these motors if in good condition!!!----Was down in the Paris area to assist a new boat owner the other day.-----Removed powerhead and lower unit for winter overhaul.----After I was done in the storage barn they said " thank you very much and have you considered teaching about outboards and boating "

Ok thanks.

 

[KodiakJack]

Trim changes the angle of attack my raising the bow. The higher the bow the less wetted area of the hull and less drag due to the friction from the water. Trimmed all the way down will get you on plane faster and is called by boaters as the "hole shot" Think of it as a short field takeoff. When running in rough water you may want the bow down to smooth out the ride as the boat well be slicing through the water especially in a V hull. Most efficient speed for most boats is at a 100 or so rpms over what it takes just to keep the boat on plane. It won't take you long to figure out trim and speed at different loads and weight distributions. There are no weight and balance calculators for small boats so it is seat of your pants and experience.

That’s very helpful, thanks. I was curious about the gas mileage one can expect, but it sounds like there’s so many variables that you just fill ‘er up and you get what you get.

 

[KodiakJack]

This line scares me the most. the motor stuff is easy.

however the flooring being replaced is most likely a "deck over" where they simply slapped a new wood deck over the rotten floor, stringers, foam and transom.

fiberglass boats from the 80's are notoriously bad with their initial build quality and 99.5% of them have rot. the 0.5% of them that do not are most likely still locked in the garage or have undergone a restoration

If it was me, I would like to know what was replaced along with the floor.

So the old wood was removed, and replaced with 5/8” pressure treated ply wood.

to verify the condition of the fiberglass, where’s the best place to look and poke? The “usual suspects”. From what I’ve seen so far, it looks and feels good, but maybe I’m not in the right areas.

 

[JimS123]

Hi all! I bought a boat!

There’s a million questions I have, I hardly know where to start!

Back in my youth, over 50 years ago, I bought a boat as well. At the time, I didn't even drive a car. In those days they had a building in each town that had racks of paper things with words written on them. I used to go to mine to study things. Haven't been there since 1982 when I got my first IBM AT.

(That's my little humor like the canoe thing...LOL)

Anywhoot, back then I read books about how to build and rig a boat, how to operate one, and most of all how to launch and retrieve one from a trailer. Watching people today at the launch ramp has convinced me the latter book must not have been read in many years.

My suggestion is to read whatever you can find. A boater's exam is a good start, but you should also take the 8-hour in-person course given by the USCGA or a Power Squadron. Most States have "Rules of the Road" and legal pamphlets. Go to a West Marine - some have boating libraries. Subscribe to a few boating magazines. Without question, join BoatUS. Its really cheap and they have quarterly magazines. Plus you won't find cheaper insurance.

Finally, spend a few Sunday afternoon hours sitting at a launch ramp. You may only see a few things that you'll want to do, but you'll see a lot of things not to do.

 

[KodiakJack]

Back in my youth, over 50 years ago, I bought a boat as well. At the time, I didn't even drive a car. In those days they had a building in each town that had racks of paper things with words written on them. I used to go to mine to study things. Haven't been there since 1982 when I got my first IBM AT.

(That's my little humor like the canoe thing...LOL)

Anywhoot, back then I read books about how to build and rig a boat, how to operate one, and most of all how to launch and retrieve one from a trailer. Watching people today at the launch ramp has convinced me the latter book must not have been read in many years.

My suggestion is to read whatever you can find. A boater's exam is a good start, but you should also take the 8-hour in-person course given by the USCGA or a Power Squadron. Most States have "Rules of the Road" and legal pamphlets. Go to a West Marine - some have boating libraries. Subscribe to a few boating magazines. Without question, join BoatUS. Its really cheap and they have quarterly magazines. Plus you won't find cheaper insurance.

Finally, spend a few Sunday afternoon hours sitting at a launch ramp. You may only see a few things that you'll want to do, but you'll see a lot of things not to do.

Ha ha, yeah that’s my fear! There’s a Food Truck down at the lake next to a boat launch that my family and I frequent in the summer. The boat ramp provides plenty of entertainment for the nearby diners. I don’t want to be that guy! Lol.

thanks for the advice, perhaps one of your Canadian counterparts can comment on what Canadian equivalents are available to us up here when it comes to the Power Squadron and BoatUS stuff.

I like the idea of subscribing to a magazine... any in particular you’d recommend? My interests lie mostly in fishing with it, so if there’s a dual purpose(ish) magazine, that’d probably be my preference.

Thanks again!

 

[dwco5051]

That’s very helpful, thanks. I was curious about the gas mileage one can expect, but it sounds like there’s so many variables that you just fill ‘er up and you get what you get.

The old rule of thumb was divide the horsepower by ten to figure fuel burn in US gallons per hour running flat out.

 

[racerone]

There usually is nothing wrong with the fiberglass itself!----The fiberglass does not rot--It is the wood ( coring ) used to give the fiberglass the strength that rots away.----Then the fiberglass then might start to crack in places.----Doing a project right now getting rid of all of the wood in transom and floor.----Replace it with composite materials.

 

[Scott Danforth]

So the old wood was removed, and replaced with 5/8” pressure treated ply wood.

to verify the condition of the fiberglass, where’s the best place to look and poke? The “usual suspects”. From what I’ve seen so far, it looks and feels good, but maybe I’m not in the right areas.

did he do just the deck, or was the transom and stringers done, and the foam re-done? pressure treated plywood is not a material of choice as the fiberglass does not like to stick to it. or is it bare pressure treated wood under carpet? if that is the case, post pics ASAP.

 

[Scott Danforth]

That’s very helpful, thanks. I was curious about the gas mileage one can expect, but it sounds like there’s so many variables that you just fill ‘er up and you get what you get.

if you want fuel economy in a boat, get one with sails and slaves pulling on oars.

an well tuned up outboard will burn 0.5# of fuel per HP per hour. so if you command WOT on your prop rated 140hp motor, you are commanding about 155hp at the flywheel. 0.5# x 155 x 1 would be 77.5# of fuel per hour. in the US, there are 6.82# per gallon, so you would burn thru 11.4 gallons

 

[JimS123]

That’s very helpful, thanks. I was curious about the gas mileage one can expect, but it sounds like there’s so many variables that you just fill ‘er up and you get what you get.

Boats are not "positive displacement" like a car. For example, if you are moving at 6 mph against a 6 mph current, you are standing still while burning up a lot of gas. Thus, lots of factors to consider. Also, as the boats get larger and the engines bigger you don't calculate MPG you calculate GPM.

As an Engineer, making mods to increase speed or economy has been a lifelong goal. So, I have lots of data. My GPS/Depthfiner/Chartplotters log in miles and hours and I record each gas fillup.

Some examples: My 16' fiberglass runabout with a 60 HP 2-stroke got on average 4.5 mpg. My 14' aluminum utility with a 25 HP 2-stroke got about 6.0 mpg. My current 15' fiberglass center console with a 60 HP 4-stroke (~same weight as the 16 footer, 2-stroke) averaged 10.0 mpg this past Summer. Big difference between 2 and 4 strokes.

Going up to larger runabouts: My 19' I/O 140 HP averaged at about 6.0 mpg. My current 19 footer with a 150 4-stroke OB (a few hundred pounds heavier) came in at 8.0 mpg this year.

Of course, the caveat is how you drive them. I punch it once in awhile, but since I know the performance curves, I usually run at the most economical cruise speed.

 

[PITBoat]

Trim changes the angle of attack my raising the bow. The higher the bow the less wetted area of the hull and less drag due to the friction from the water. Trimmed all the way down will get you on plane faster and is called by boaters as the "hole shot" Think of it as a short field takeoff. When running in rough water you may want the bow down to smooth out the ride as the boat well be slicing through the water especially in a V hull. Most efficient speed for most boats is at a 100 or so rpms over what it takes just to keep the boat on plane. It won't take you long to figure out trim and speed at different loads and weight distributions. There are no weight and balance calculators for small boats so it is seat of your pants and experience.

So down when you start, and gradually up to get best speed for whatever RPM you've chosen to cruise at. If the bow is bouncing you've prob gone too far up.
On a glassy day trying for max speed and trimming up in increments, you'll finally hit a place where you've passed the optimum and you begin to lose speed.
I found it simpler in an airplane. If you're having to pull, trim it up. If you're having to push, trim it down. Done, 'til you change speeds.