Mercury 6HP vs 9.8 HP

[Crkgrl]

I have a 12 foot Smokercraft. Have used a 9.8 Merc before and it is plenty, if not too much power. Also heavy for a 5'2" girly girl to move about.

If I go with the 6 HP will my speed be drastically reduced? Never is much in the boat but me at 120 lbs.

Dont remember the phyics or whatever that would adequately describe the difference between the two.

Is the 6 HP any lighter to lug about?


Thanks for any help.

 

[ck85abc3]

Re: Mercury 6HP vs 9.8 HP

What year/years are they?

For brand new motors...

9.9 = 84 lbs

6 = 55 lbs

 

[beerfilter]

Re: Mercury 6HP vs 9.8 HP

I run a 90 model Merc 9.9 on my 12' Appleby , and it is all it wants .
My 69 Johny 4 is way underpowered , will barely make progress upstream in high water , but , is fine for pushing it around small lakes/ponds .

Are you having to portage the rig around beaver dams/bars/rapids ?

There is a weight penalty to be paid for the metal to contain and control a given amount of power .

A 6HP may serve you better and be easier to handle .
Then again , it may not be worth the weight savings if you have to run against wind/current for any distance .

It boils down to how much power/speed you are willing to sacrifice , for a little more ease rigging and unrigging .

A 40% loss in power and speed may be worth the reduction of 20 Lbs of weight to handle . Then again , maybe not .

It is hard to give a direct answer without exactly knowing where you are fishing/boating , the conditions , etc ...

 

[Crkgrl]

Re: Mercury 6HP vs 9.8 HP

Thanks so much for the help. The owner of the 6 HP believes it is a 1966. My 9.8 HP is a 1974. I use the 9.8 for puttering around on the Ohio River.

I am not usually out in overly windy or swift current conditions. Many times I can not use the full power of the 9.8, due to conditions. It is fun though, to occasionally run it at full bore.

How much loss of speed could I expect in ideal conditions? 5MPH? 10?

An added question: Can I assume the 1966 works on the same fuel mix? 50:1? Besides the obvious, can you think of anything I should look for when inspecting the 6HP for possible purchase?

Ease of start, spark plugs, obvious wear, water pump, etc come to mind, but I am kind of a rookie at purchasing used motors. Trying to figure out how to test it's shifting ability without having it take off through the guys yard.

 

[beerfilter]

Re: Mercury 6HP vs 9.8 HP

Check the lower unit for water / dirty lube .
Water will be obvious as a milky sludge , dirty black lube is a sign of neglect .

Check the compression .
100 PSI is excellent , no more than 5% difference between cylinders .

If below 80 PSI , pass on it

Spark plugs should be a medium brown to light tan .
If they are coated with black carbon it means a rich condition .
If they are white and look corroded you have a severe lean condition .
Both are indications of fuel system/carb problems , and , it WILL destroy the powerhead very quickly .

Make sure there is water , in a steady stream , from the telltale , or "peehole" .
If not the impellor/water pump needs replaced , although it is a good idea to replace it every year .

Look for peeling or discolored paint on the powerhead .
This is usually due to overheating .

SWAG says that 6 HP Rude should push your rig ~ 10-15 MPH at full throttle .
Ok for you and a little tackle .
Give any passengers a paddle to help .

IMO , I'd want all the power the hull is rated for at my disposal .
I wanna be able to get outa' Dodge if the weather turns , as it often does .
Trying to beat a storm with an underpowered rig is leaving an open invitation to Murphy .



My 9.9 erc pushes my Appleby just shy of 30 MPH .

 

[Crkgrl]

Re: Mercury 6HP vs 9.8 HP

Thanks for all the help. I had to pass on the 6HP. Many issues, that even my novice mind could fathom.

The gas connector at the engine had been modified and was leaking all over the place. One of the armatures for cowling release was gone. Motor was spewing oil, but not water.

That was enough for me. I offered a lot less, thinking it would be a project, but the folks wouldnt take it. I will keep looking.

Thanks for the break down on the MPH, 6-9.8. Seems substantial. I am in the process of rehabbing the 9.8.

Okay, here is another rookie question: How do you check the compression? Is there a compression testing device?

 

[jessper]

Re: Mercury 6HP vs 9.8 HP

There is a tester used for compression testing. They are relatively cheap. Harbor freight has one for 9.99. Part 92720-1vga. They might sell them here also.

 

[Crkgrl]

Re: Mercury 6HP vs 9.8 HP

Thanks for the help. I will look into that.