Reply
 
Thread Tools Search this Thread
 
Old 30 August 2015, 23:59   #1
Member
 
Country: Canada
Length: under 3m
Join Date: Aug 2015
Posts: 15
Moving too slowly 9.5 hp, 630lbs, 10ft achilles??

I picked up a 9.5 hp johnson like in the link below and had it out on the water today. I know for a fact the motor was not producing full power, the rpm was unstable and it appears the little plastic cylinder that rides between the timing plate and the throttle lever was missing, but it would be safe to say that we were getting a good 7-8hp.

I'd estimate the total weight of everything including boat and motor to be around 630lbs and it looked like we were moving less than 10km/h. The motor appeared to be doing a lot of splashing around instead of pushing; the wake was huge compared to some similar boats that appeared to be moving faster. I do not think the boat picked up on a plane either, instead the bow was always pointing about 10 degrees out of the water at full throttle.

I want to know what is wrong with my setup, the max this boat is rated for is 10 hp so it would be kind of ridiculous if it could not plane with a 9.5hp motor. The cavitation plate sat about 1 or 2 inches under the water when not moving if that is important.

The motor model
http://sportfishermans-service.com/w...4/IMG_3445.jpg

The boat model
http://www.skifflife.com/files/2015/...HV_600x450.jpg

The actual propeller, it's in rough shape and I want to know if it's matched to the motor or not.

http://i.imgur.com/qm0UU7h.jpg
__________________

__________________
nabiul is offline   Reply With Quote
Old 31 August 2015, 00:26   #2
Member
 
Country: USA
Town: S. Carolina
Boat name: D560
Make: Avon
Length: 5m +
Engine: 2016 Merc 115hp CT
Join Date: Aug 2013
Posts: 1,121
I had a 1966 MQ11C (Johnson 9.5) and was easily able to move an Avon 315 Rollaway at about 20 mph... it had about 70 psi of compression left in it.

Sounds like your outboard is broken just like you said? Check the compression too.
__________________

__________________
Richard
Gluing geek since 2007
office888 is offline   Reply With Quote
Old 31 August 2015, 01:53   #3
Member
 
Country: Canada
Length: under 3m
Join Date: Aug 2015
Posts: 15
How fast would you estimate this boat is moving? I think this is close to what is happening to me.

__________________
nabiul is offline   Reply With Quote
Old 31 August 2015, 03:08   #4
RIBnet admin team
 
willk's Avatar
 
Country: Ireland
Make: Redbay Boats
Length: 9m +
Engine: 370hp
Join Date: Feb 2008
Posts: 12,928
RIBase
Quote:
Originally Posted by nabiul View Post
I picked up a 9.5 hp johnson like in the link below and had it out on the water today. I know for a fact the motor was not producing full power, the rpm was unstable and it appears the little plastic cylinder that rides between the timing plate and the throttle lever was missing, but it would be safe to say that we were getting a good 7-8hp.
I'd estimate the total weight of everything including boat and motor to be around 630lbs and it looked like we were moving less than 10km/h. The motor appeared to be doing a lot of splashing around instead of pushing; the wake was huge compared to some similar boats that appeared to be moving faster. I do not think the boat picked up on a plane either, instead the bow was always pointing about 10 degrees out of the water at full throttle.
I want to know what is wrong with my setup, the max this boat is rated for is 10 hp so it would be kind of ridiculous if it could not plane with a 9.5hp motor. The cavitation plate sat about 1 or 2 inches under the water when not moving if that is important.The actual propeller, it's in rough shape and I want to know if it's matched to the motor or not.
You seem to have your own query well under control!

The engine isn't making power, the prop is scuffed and the boat is overloaded. I'm gonna guess very little of the weight was forward of the centerline as well?

You don't say what equipment and passengers were onboard, or what air pressure was in the boat - it may help us? Were you using a tiller extension?
__________________
"Who knows what evil lurks in the hearts of men?"
.
willk is offline   Reply With Quote
Old 31 August 2015, 03:21   #5
RIBnet admin team
 
Poly's Avatar
 
Country: UK - Scotland
Boat name: imposter
Make: FunYak
Length: 3m +
Engine: 2 stroke YAM 20 HP
MMSI: 235089819
Join Date: Sep 2005
Posts: 10,114
Quote:
Originally Posted by willk View Post
You seem to have your own query well under control!

The engine isn't making power, the prop is scuffed and the boat is overloaded. I'm gonna guess very little of the weight was forward of the centerline as well?

You don't say what equipment and passengers were onboard, or what air pressure was in the boat - it may help us? Were you using a tiller extension?
Nor do you suggest if you tried different trim settings.

You say the ant ventillation plate was below the water when stationary, but how does it compare to the bottom of the hull?

Even when new that engine didn't put out as much HP as a modern 9.5 as the method of measuring it has changed.
__________________
Poly is offline   Reply With Quote
Old 31 August 2015, 03:39   #6
Member
 
Country: UK - England
Length: 3m +
Join Date: Sep 2008
Posts: 2,251
You've been given plenty of likely things to look at but while you are looking...

I assume there is either a wooden ridge under the floor or an inflated tube? Just in the photo the V does not look that big...

Secondly could there be any prop slip ? The prop sits on a rubber 'gear' for want of a better description ... If that's damaged it results in surges in revs.
__________________
ShinyShoe is offline   Reply With Quote
Old 31 August 2015, 04:34   #7
Member
 
Country: UK - England
Town: Lincolnshire
Boat name: Mousetrap
Make: Zodiac Cadet 310S
Length: 3m +
Engine: Mariner 4 stroke 9.9
Join Date: Sep 2014
Posts: 221
First thing I'd check is the tilt of the motor. Most motors have a 3 position stop. When I first fitted my outboard I had it on the middle setting. The first time I tried it at full speed it sounded and acted like the clutch was slipping. I worked out that the prop was sucking air in. I dropped the tilt to the lowest setting and now it works fine.

Second thing on any inflatable is to get the weight distribution right. That usually means moving crew and baggage forwards.
__________________
Mikefule is offline   Reply With Quote
Old 31 August 2015, 11:07   #8
Member
 
Country: Canada
Length: under 3m
Join Date: Aug 2015
Posts: 15
Two passengers on board, about 230lbs each; we tried both at back and one at back and one close to the bow. My friends also went out, about 160 at back and maybe 230 right on the bow; they moved quicker but no planing.

We started with a neutral trim and changed to trimmed out which appeared to make us move faster since the bow was climbing so much. The plate was probably level with the bottom of the transom, but the tubes are much lower. How much power would you estimate it to be compared to today? I'm also looking at an old ted williams air cooled single cylinder 7hp motor as a backup since I can't get the 9.5 on the boat by myself.

There is a standard inflatable keel that almost flattens out at the transom. I did not know that the rubber prop holder could slip, it is likely worn out, I will take a look.

It's difficult to have all the weight forwards on such a small boat and each of us weighing so much.
__________________
nabiul is offline   Reply With Quote
Old 31 August 2015, 11:11   #9
Member
 
Country: USA
Town: S. Carolina
Boat name: D560
Make: Avon
Length: 5m +
Engine: 2016 Merc 115hp CT
Join Date: Aug 2013
Posts: 1,121
Quote:
Originally Posted by nabiul View Post
Two passengers on board, about 230lbs each; we tried both at back and one at back and one close to the bow. My friends also went out, about 160 at back and maybe 230 right on the bow; they moved quicker but no planing.

We started with a neutral trim and changed to trimmed out which appeared to make us move faster since the bow was climbing so much. The plate was probably level with the bottom of the transom, but the tubes are much lower. How much power would you estimate it to be compared to today? I'm also looking at an old ted williams air cooled single cylinder 7hp motor as a backup since I can't get the 9.5 on the boat by myself.

There is a standard inflatable keel that almost flattens out at the transom. I did not know that the rubber prop holder could slip, it is likely worn out, I will take a look.

It's difficult to have all the weight forwards on such a small boat and each of us weighing so much.
Those old Ted Williams engines are junk... I would recommend against it. There's a reason why they sell for $75 - $150.

It should plane with that 9.5 hp. Those old Johnson 9.5hp are awesome.

Check the compression and check your RPMs.
__________________
Richard
Gluing geek since 2007
office888 is offline   Reply With Quote
Old 31 August 2015, 11:27   #10
Member
 
Country: Canada
Length: under 3m
Join Date: Aug 2015
Posts: 15
Any specific reasons why they are bad, I've already arranged to meet with the seller? If it is junk then it is being priced like a good johnson or evinrude at $250 (inflated prices in southern ontario).
I was mainly looking at it because of how light it is.

I'm actually getting rid of a 5hp evinrude angler today and sold a johnson hd25 on saturday. I miss the little johnson, so light, idles at low low revs and burned pretty much any mix; I'm looking for something to replace it.
__________________

__________________
nabiul is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 08:20.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.