Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 25-05-2011, 13:01   #1
Registered User
 
janders's Avatar

Join Date: Mar 2008
Location: Seattle, WA
Boat: Caliber 40
Posts: 154
Avon 280 RIB w/ 15HP Outboard

Hey all, we're in the process of upgrading the dink's outboard. We targeted a 9.9hp 2-stroke but I've found a couple 15hp 2-strokes that look pretty attractive.

My dilema: the dinghy is an Avon 280 fiberglass RIB and rated at 10hp. What's the perils of putting a 15hp on this dinghy? I'm open to strengthening the transom with a bit of extra glass if need be.

That 15hp is looking pretty sexy.

Jason
__________________

__________________
s/v Hello World
Caliber 40 hull #55
janders is offline   Reply With Quote
Old 25-05-2011, 13:08   #2
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Cowes (Winter), Baltic (Summer) (the boat!); somewhere in the air (me!)
Boat: Cutter-Rigged Moody 54
Posts: 19,750
Re: Avon 280 RIB w/ 15HP outboard

I wouldn't do it if I were you. The boat is rated for 10hp for a reason -- weight of the motor, stability under power. I've found that the maximum rated hp for ribs is really very much the most power you can use.

We had a 15hp two stroke on a rib that size on the old boat. We figured that since it was a two stroke, and the rib was rated for a 10 hp four stroke, it could handle the weight. Well, it couldn't, and couldn't use the power, either. We sold the 15hp at a loss, changed to a 5hp, and were very happy.

On the new boat we have an Avon 340 rib with its maximum rated hp -- a 25 horsepower two-stroke. It's just the right amount of power -- you just about need full throttle to get it on a plane with the maximum rated load on board.

If I were you, I would stick to the rating.
__________________

__________________
Dockhead is offline   Reply With Quote
Old 25-05-2011, 13:41   #3
Mooderator
 
capngeo's Avatar

Cruisers Forum Supporter

Join Date: Jul 2010
Location: Key West & Sarasota
Boat: Cal 28 "Happy Days"
Posts: 4,211
Images: 12
Send a message via Yahoo to capngeo Send a message via Skype™ to capngeo
Re: Avon 280 RIB w/ 15HP outboard

I'm one of those guys who ALWAYS overpower my dinks. A lot of times (especially with the 2 strokes) the next size HP rating was exactly the same weight and dimension, as the HP increase was carbs, intakes etc.

The naysayers will point out the dangers of overpowering, which if it were going to be used by a 15 year old, I'd agree. As adults we can hopefully restrain ourselves from unnecessary WOT. Having the extra HP for emergencies or extra heavy loads is damned handy. Not saying drop a 50 on the back of your dink BUT a 15 if comparable in weight, shouldn't be a huge problem.

Throw the above out the window on roll-up boats BTW... RIBs are much stronger!
__________________
Any fool with a big enough checkbook can BUY a boat; it takes a SPECIAL type of fool to build his own! -Capngeo
capngeo is offline   Reply With Quote
Old 25-05-2011, 13:59   #4
Registered User
 
janders's Avatar

Join Date: Mar 2008
Location: Seattle, WA
Boat: Caliber 40
Posts: 154
Re: Avon 280 RIB w/ 15HP outboard

Based on the engine weight alone, I think a 15hp two stroke would be fine. From what I can tell, the 15hp two stroke weighs in at around 80lbs. Whereas a 9.9hp four stroke weighs in at over 110lbs.

[edited to add:] A Mercury 9.9hp seems to be the same engine as a 15hp plus some sort of fuel governing. It weighs the same as the 15hp.

I guess the concern then would be how much thrust the engine is putting out and whether the transom is strong enough to handle it. I don't have a sense of whether or not that extra 5hp is a problem on a fiberglass RIB that's in good shape. I wouldn't consider this with a roll-up or inflatable floor.
__________________
s/v Hello World
Caliber 40 hull #55
janders is offline   Reply With Quote
Old 25-05-2011, 14:26   #5
Senior Cruiser
 
Vasco's Avatar

Cruisers Forum Supporter

Join Date: Apr 2004
Location: Toronto
Boat: CS36Merlin, "La Belle Aurore" Ben393 "Breathless"
Posts: 7,138
Re: Avon 280 RIB w/ 15HP outboard

Go for it. One trip to the Bahamas will open your eyes as far as hp and size of small boats. The Bahamians love to get their boats completely out of the water, just skimming along on the ob skeg.
__________________
Rick I
Toronto in summer, Bahamas in winter.
http://groups.yahoo.com/group/beneteau393/
Vasco is online now   Reply With Quote
Old 25-05-2011, 19:55   #6
Registered User
 
Laidback's Avatar

Join Date: Jun 2007
Posts: 853
Re: Avon 280 RIB w/ 15HP outboard

Quote:
Originally Posted by Vasco View Post
Go for it. One trip to the Bahamas will open your eyes as far as hp and size of small boats. The Bahamians love to get their boats completely out of the water, just skimming along on the ob skeg.
The USCG may say that AVON only rate the 280 for max HP of 10.

Length Beam Weight Capacity Max Engine Max
Overall Overall Boat Persons Payload Remote Tiller Performance
ft/in m ft/in m lbs kg lbs kg hp kW hp kW mph kph
R 280 Rib 92 2.80 53 1.60 135 61 3
+ child 1014 460 10 7.5 10 7.5 19 30
__________________
Laidback is offline   Reply With Quote
Old 07-06-2011, 15:51   #7
Registered User

Join Date: Mar 2011
Posts: 253
I have a Honda 9.9. It is the same motor as the 15 horse except it comes with a screw preventing the throttle from opening up. if you take the screw out, it gets you to about 13.5 HP, there is a slight difference in the carburetor jets which will give you the extra 1.5

Have it on a 290 RIB rated for a 10 and it is a lot of power, but With the boat loaded, it does not hurt.

The reason they manufacture 9.9s is because there are certain lakes that limit HP to under 10. maybe put the screw back in when your kids use it!

anyway, have you guys found any good mounting solutions? The out of the box stern rail mounts are all limited to 100 lbs. My Honda Is 108 without fluids. Also, any boat I've seen that mounts outboards on the stern rail gets a ton of stress cracks on the deck under the stanchions.

Has anyone had success storing a 110lb+ outboard?

Thanks!
__________________
shamrock is offline   Reply With Quote
Old 07-06-2011, 22:29   #8
Registered User

Join Date: Jun 2010
Location: San Diego
Boat: Pacific Seacraft Crealock 37
Posts: 60
Re: Avon 280 RIB w/ 15HP Outboard

Quote:
Originally Posted by janders View Post
Hey all, we're in the process of upgrading the dink's outboard. We targeted a 9.9hp 2-stroke but I've found a couple 15hp 2-strokes that look pretty attractive.

My dilema: the dinghy is an Avon 280 fiberglass RIB and rated at 10hp. What's the perils of putting a 15hp on this dinghy? I'm open to strengthening the transom with a bit of extra glass if need be.

That 15hp is looking pretty sexy.

Jason
A few years back I had the AVON 280 RIB with a Mercury 15 HP. The motor replaced a dead 9.9 HP. I went with the 15 HP as I was trying to get the boat
up on plane with 2 divers and gear. No luck. Needed a longer boat with weight the extra HP alone would not do it. Eventually went with a roll-up Avon 3.40 with the same motor and was able to easily get it up on plane with 2 divers.

Without substantial weight in the boat you need to careful about how quickly you throttle up as it can get a bit squirly.

Marc Hall
"Crazy Fish" , Crealock 37 based in San Diego
__________________
MarcHall is offline   Reply With Quote
Old 07-06-2011, 22:47   #9
CF Adviser
 
Bash's Avatar

Cruisers Forum Supporter

Join Date: Dec 2008
Location: sausalito
Boat: 14 meter sloop
Posts: 7,260
Re: Avon 280 RIB w/ 15HP Outboard

Quote:
Originally Posted by janders View Post
That 15hp is looking pretty sexy.
Sexy?

I once saw a guy flip an overpowered dink where the bow went aft and the stern went forward.

It was ugly.
__________________

__________________
cruising is entirely about showing up--in boat shoes.
Bash is offline   Reply With Quote
Reply

Tags
avon, outboard, rib

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Small (Very Old!) Avon RIB - What to Look for ? David_Old_Jersey Auxiliary Equipment & Dinghy 2 03-09-2010 15:20
Advice on Avon 310 RIB Lite judy General Sailing Forum 6 12-07-2010 21:34
Avon RIB Leaking jim_thomsen Auxiliary Equipment & Dinghy 5 21-12-2009 15:54
'95 Avon Rover 310 RIB Valve Leak bristolsailor Auxiliary Equipment & Dinghy 1 13-07-2009 22:08
For Sale: Avon Rover 310 w/Honda 15hp Electric Start Beach Cruiser Classifieds Archive 0 13-07-2009 14:17



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 09:35.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.