|
24 October 2009, 21:23
|
#1
|
Member
Country: UK - England
Length: no boat
Join Date: Oct 2009
Posts: 521
|
Avon Rover 340 - 25hp 2-stroke or 20hp 4-stroke?
Evening all. New member here seeking some advice. Have just bought my first RIB (in fact, my first boat), a 2002 Avon Rover 340. It is currently a bare boat (ie no console or seating) and is fitted with an older Mariner Marathon 15hp. My intention is to fit a side console and bench seat, and to replace the Mariner with a larger, remote outboard.
The transom is rated to a max 25hp and max engine weight of 62kg. This effectively gives me the choice of a 25hp 2-stroke, or a 20hp 4-stroke. I'm not too bothered about out and out speed, but don't want to buy a 4-stroke and then find it's not powerful enough to get the boat up on the plane with two adults aboard.
Can anyone advise as to whether the 20hp 4/s would suffice, or would I need to go with a 25hp 2/s ?
Would appreciate your opinions, particularly from anyone with similarly sized and equipped RIBs.
__________________
|
|
|
24 October 2009, 22:42
|
#2
|
Member
Country: UK - England
Length: no boat
Join Date: Oct 2009
Posts: 521
|
Incidentally, I don't have the budget for a brand new engine so will be looking for a good 3 to 6 year old motor. Other than Ebay and Boatsandoutboards.com, can anyone suggest any other sites listing/advertising a good selection of (UK located) used outboards?
Cheers!
__________________
|
|
|
25 October 2009, 14:05
|
#3
|
RIBnet admin team
Country: UK - Scotland
Boat name: imposter
Make: FunYak
Length: 3m +
Engine: Tohatsu 30HP
MMSI: 235089819
Join Date: Sep 2005
Posts: 11,632
|
3.9 m boat with console (presumably heavier than yours) with 20HP 2str Yam happily planed in calm weather with 4 adults and 2 kids on board, 30L fuel, gear etc. So don't think you should have two much trouble whichever engine you opt for.
__________________
|
|
|
25 October 2009, 20:15
|
#4
|
Member
Country: Other
Town: Lima-Peru
Boat name: Nautile
Make: Sea Rider 450 Rib
Length: 4m +
Engine: Tohatsu 5/18/30 HP
Join Date: Sep 2007
Posts: 1,998
|
Quote:
Originally Posted by NSS
Incidentally, I don't have the budget for a brand new engine so will be looking for a good 3 to 6 year old motor.
|
If easy to find, go for a Mariner or Tohatsu 2 strokes 25 HP and retune it to 30 HP for peanuts, is same size & weight as a Tohatsu 30 HP, 52 kilos with extra 5 HP just in case.
Happy Boating
__________________
|
|
|
25 October 2009, 21:40
|
#5
|
Member
Country: UK - England
Length: no boat
Join Date: Oct 2009
Posts: 521
|
Thanks guys. Must admit, I'm more inclined toward the 4-stroke 20hp option than the 25hp 2-stroke, so good to hear your experience with a 20hp on a loaded 3.9 RIB, Polwart.
Howver, I guess it's a case now of seeing what I can find within my budget.
I'd still appreciate any recommendations on good sources for used motors. Cheers!
__________________
|
|
|
25 October 2009, 21:51
|
#6
|
RIBnet admin team
Country: UK - Scotland
Boat name: imposter
Make: FunYak
Length: 3m +
Engine: Tohatsu 30HP
MMSI: 235089819
Join Date: Sep 2005
Posts: 11,632
|
Quote:
Originally Posted by NSS
Thanks guys. Must admit, I'm more inclined toward the 4-stroke 20hp option than the 25hp 2-stroke, so good to hear your experience with a 20hp on a loaded 3.9 RIB, Polwart.
Howver, I guess it's a case now of seeing what I can find within my budget.
I'd still appreciate any recommendations on good sources for used motors. Cheers!
|
Just realised you are talking RIB not SIB here. I'm sure you'll still get on the plane (I have an oddball boat that is neither but does have a rigid reasonable v-hull but lighter that a typical RIB).
__________________
|
|
|
26 October 2009, 12:52
|
#8
|
Member
Country: UK - Scotland
Boat name: Wildheart
Make: Humber/Delta Seasafe
Length: 5m +
Engine: Merc 60 Clamshell
MMSI: 235068449
Join Date: Apr 2007
Posts: 4,671
|
Other plus side to the 4- stroke if you aren't bothereda bout flat out top sped is the 4- stroke will likely be quieter & more frugal at lower rpms.
If you get the prop pitch right planing should be no problem.
I had no issues with a Suzi DT25 on an Avon SR4. Said engine may be available soon, depending what happens with the Merc rebuild! (i.e once I know for sure that it's not going to be needed for more "standby duty" while I look for a replacement 60)
__________________
|
|
|
26 October 2009, 15:46
|
#9
|
Member
Country: UK - England
Town: Dorset & Hants
Boat name: Streaker/Orange
Make: Avon/Ribcraft
Length: 4m +
Engine: 50Yam/25 Mariner
Join Date: Apr 2007
Posts: 5,551
|
A mate runs a 20 Honda on a 3.5 & regularly does 20 mile runs to the Isle of Wight & back - so reckon you wil be fine. You wont be going super quick , but I think will plane quite happily as I think the hulls are quite flat so will plane with a lower HP than say an SR4 .
__________________
|
|
|
27 October 2009, 10:30
|
#10
|
Member
Country: UK - England
Length: no boat
Join Date: Oct 2009
Posts: 521
|
Thank you all for your comments. Much appreciated.
__________________
|
|
|
17 November 2009, 18:09
|
#11
|
Member
Country: Cayman Islands
Length: 3m +
Join Date: Nov 2009
Posts: 1
|
I don't know if I can agree with that advice.
I have that exact same RIB -- Avon 340 -- which I use as a tender for a large sailing yacht. It has a Mariner 25 horsepower 2-stroke and jocky console. It planes happily and efficiently with up to about four people and no gear, but beyond that load it starts to struggle. With five adults and some stuff it will not plane.
I would not want less than 25 horsepower, myself, on that boat. It's a real plodder when not planing.
2-stroke or 4-stroke is a matter of taste, but I like 2-strokes myself, for their unbeatable power to weight ratio, and simplicity. You give up something on economy and perhaps longevity; these will be bigger issues if you use your RIB for any kind of continuous duty. For a tender it's not a big problem. The Mariner is quite quiet; I don't know about other 2-strokes.
__________________
|
|
|
18 November 2009, 09:29
|
#12
|
Member
Country: UK - England
Town: Ipswich
Boat name: Jammy Dodger
Make: Avon Adventure 7.20
Length: 7m +
Engine: 200 Yamaha
Join Date: Dec 2008
Posts: 365
|
Id defiantly go for the 25 2 Stroke, Had a Mercury 25 2 Stroke on my old rib - Valiant 3.80
Did about 27 knots!
__________________
|
|
|
06 May 2013, 14:37
|
#13
|
Member
Country: UK - Scotland
Make: Zodiac
Length: 3m +
Engine: Outboard, 20hp
Join Date: Apr 2013
Posts: 4
|
Hi, I realise this is an old posting, but just joined the forum and I am considering getting a new Zodiac Cadet 340 RIB with trailer. So wondering about outboard options. Suzuki 20hp was recommended but wondering about 4 stroke vs 2 stroke and possibly going for smaller 15 hp and not necessarily Suzuki. Having seen your discussion from 2009 I'm guessing you now know what worked for you. Any thoughts that might help me in my decision?
__________________
|
|
|
07 May 2013, 07:49
|
#14
|
Member
Country: UK - England
Town: Thornbury
Make: Avon Searider 4m
Length: 4m +
Engine: 50hp tohatsu tldi
Join Date: Sep 2012
Posts: 648
|
even if you go for 20hp, I would still look for a 2 stroke! I think for smaller crafts the advantages outweigh the disadvantages. My 25hp 2 stroke is fine on fuel and I was surprised I.e. pulled a knee boarder for 1 hour and a half at 3/4 throttle and I only used a few liters.
With the 2 stroke you will have more talk so will be able to take a bigger load, you will have better acceleration, better top end speed. Once you got your wind in the hair flying along at 30 knots (one person on board) you won't even notice the extra noise
__________________
|
|
|
08 May 2013, 09:49
|
#15
|
Member
Country: UK - Scotland
Boat name: Wildheart
Make: Humber/Delta Seasafe
Length: 5m +
Engine: Merc 60 Clamshell
MMSI: 235068449
Join Date: Apr 2007
Posts: 4,671
|
Everything else aside, on a "small" boat weight distribution is crucial, and the extra Kg will be noticed. Alsio should you decide not to use the trailer the extrra weight will be noticed when lugging the engine around, and 4- strokes are more fussy as to how you lay them down in the back of the car......
Two reasons to actively go 4- stroke. If you do a lot of "pottering" / fishing the 4 will drink less at low RPM, and will be a, lot quieter. If you spend the time razzing about with a wide open throttle, chances are the difference will be negligible.
__________________
|
|
|
08 May 2013, 10:05
|
#16
|
Member
Country: UK - England
Length: no boat
Join Date: Oct 2009
Posts: 521
|
I originally fitted a Tohatsu 18hp 4-stroke, but later upgraded to a Suzuki DF25 as the 18 struggled to push the boat over the 'hump' with two or more aboard. The 25 made a big difference, and fuel usage actually dropped as it would happily hold on the plane at lower revs than had been needed with the Tohatsu.
Personally I preferred 4-stroke over 2 for the reduction in noise and exhaust fumes, though I accept that a 2-stroke may well have improved the ability to get on the plane and the weight distribution. The Avon had a power and weight limit for the transom so worth checking whether the same is true for the Zodiac Cadet as this may restrict your choice.
__________________
|
|
|
08 May 2013, 10:47
|
#17
|
Member
Country: UK - Scotland
Make: Zodiac
Length: 3m +
Engine: Outboard, 20hp
Join Date: Apr 2013
Posts: 4
|
Thanks for the advice. It has helped to narrow down choices, so currently thinking I'll go for the new Suzuki 20hp 4-stroke at 44kg. Max allowed is 25hp, max recommended is 20hp.
__________________
|
|
|
08 May 2013, 19:11
|
#18
|
Member
Country: UK - England
Length: no boat
Join Date: Oct 2009
Posts: 521
|
Quote:
Originally Posted by Island Ribber
Thanks for the advice. It has helped to narrow down choices, so currently thinking I'll go for the new Suzuki 20hp 4-stroke at 44kg. Max allowed is 25hp, max recommended is 20hp.
|
If you can afford a 25hp I'd go for it. It is heavier than the 20hp, but won't increase overall laden weight (boat + engine + crew) by the 20% that you'll be gaining in power, and it's costly to buy a 20 and then wish you'd gone for the 25 (which is effectively what I did).
__________________
|
|
|
|
Posting Rules
|
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
HTML code is Off
|
|
|
|
Recent Discussions |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|