Newbie questions about my Glassmaster

[jamez]

First of all, this is our boat, and I have been on a boat a total of 3 times in my entire life. So I have some questions.

We got the boat out on the lake today and took my wife's grandfather with us. He's not an expert, but he has quite a bit of experience with boats.
Our 1974 Glassmaster is 18' long, and we have a 150HP motor. Today we had 4 adults in the boat, and my wife's grandfather thought we should be going faster than we were.

I took some pics of the gauges while at full thottle.

1.) The RPMs never made it higher than 35. Even though the gauge indicates it is a tachometer, is it really a tach? Why is a tach necessary? Why isn't it a speedo?

2.) The previous owner told us that the "Trim" doesn't work. My wife's grandfather also thought that the boat wasn't "planeing" properly, as the front was sitting high. Is the "Trim" necessary? Do we need to have it fixed/looked at?

3.) What are these?...

4.) ... and why are the ones on the starboard side pointing in the opposite direction?

Thanks in advance to those who answer my questions?
I look forward to becoming a better informed boater.

 

[ParallaxBill]

Re: Newbie questions about my Glassmaster

jamez, your boat looks just like mine and if it has the original inline 250 cubic inch 6 cylinder mercruiser it should have 165 HP.

A tach is far more useful in determining boat performance than a marine speedometer. Speedometers are notoriously inaccurate in boats. If your motor is a 165 HP mercruiser you should be turning between 3,900 and 4,300 rpm at wide open throttle with your normal loading of your boat. Your temperature gauge must not be working because it should be registering from 140-160 degrees. You'll need to fix that.

The trim is very important for boat performance since it enables the boat to run in the correct attitude on the water. Bow too far down creates drag and is hard on the engine. Bow too high will cause handling problems such as porpoising and cavitation of your prop on turns. Cavitation is when your prop is picking up air instead of water.

Those ducts you see on the rear of your boat are for ventilating the engine bilge. Your boat should also have an electric powered blower for evacuating explosive engine fumes from that area under the engine cover before start up. If gas fumes are laying in there and you get a spark you will probably blow up your boat. Not kidding at all here.

Search my posts in this forum for more info on your boat and direct all your engine/outdrive questions to the I/O forum. Those guys know their stuff and can help you get your's running safely. I know how to tune the 165's well so you can also contact me or post more questions here about your Glassmaster Tarpon.

 

[ParallaxBill]

Re: Newbie questions about my Glassmaster

BTW, you adjust your trim (once you get it working) to run maximum rpms at whatever speed you want to run at. It's a feel thing too since you will be adjusting the trim for ride comfort also.

G'luck!

 

[jamez]

Re: Newbie questions about my Glassmaster

I looked at our motor more closely yesterday, and it's an OMC 140HP.

What goes into fixing the temp gauge and trim?

What are we looking at "ballpark price" to fix these?

 

[ParallaxBill]

Re: Newbie questions about my Glassmaster

I looked at our motor more closely yesterday, and it's an OMC 140HP.

What goes into fixing the temp gauge and trim?

What are we looking at "ballpark price" to fix these?

Best place to ask about that is on the I/O forum. But check your wiring for both first.