the right size outboard for a sr5.4

tim2658 · 22 February 2009, 15:21

i hope someone can help i have a EX MOD 5.4 i was going to put a merc 90hp four stroke but looking at info on it i think it might be to heavy, but today i have been offered a mariner 60hp four stroke big foot is this to small there will only be about four adults at the most on her so how do the think she will go cheers tim

outboardtech · 22 February 2009, 15:30

tim sorry is this a 5.4 metre rib you are talking about ? cheers

tim2658 · 22 February 2009, 15:32

hi yeah a 5.4 m avon cheers

outboardtech · 22 February 2009, 15:44

tim the 90 will be better no doubt . Im just going to check if that boat will take that engine regarding weight . How ids the boat set up ? single cosole , double jockey seat ? just thinking of the weight

tim2658 · 22 February 2009, 15:48

it has a double four man console with a 60l tank built under but right up forward, But no aframe or other bits.

Poly · 22 February 2009, 16:06

TIM - I ain't a searider expert - but as you probably know there are quite a few here who are. I suspect that they will want to know if it still has the flooding hull or not.

doggypaddle · 22 February 2009, 16:12

Max transom weight for a 5.4 searider is 175KGS. i assume EX MOD 5.4 is a searider?
Mercury 4 stroke is over 180KGS dry.
the 60 is 112KGS.
seariders were designed in the days of twostrokes when engines were a bit lighter.
A 60 would be fine, i believe the MOD now use 75 4 stroke mariners. which are within the transom weight.
the 90 is a tad heavy, but its so close that maybe if your insurance company are happy with an overweight engine then it would be OK.
Personally i wouldnt want any more weight on the back of my SR than the 90 YAMAHA 2 st. Its nicely balanced like that.
Turbodiesel has a bit of experience in this department and may be able to give a definitive answer.

outboardtech · 22 February 2009, 16:13

no tim that 90 will be toooooo heavy I think . if its the yami based engine powerhead 4 cylinder then its a heavy bugger . On the other hand most BIG FOOT engines we fit to boats are for a big displacement hull not a up and out the water rib . You really need a 60 thats a standard gearbox with a smaller pitch prop . but then again it all depends what you want to use it for . if its just to get out with familiy and pot arond then the big foot will be probably ok .

matt h · 22 February 2009, 16:15

the bottom line is Avon say Total engine weight not to exeed 175 kg ,and thats the limit, (sure they will take a bit more before it implodes) but really an engine that weighs in the 135kg range and less is ideal, you will find because of the weights issue that most put on 75 or 90 two strokes for a even weight,

Nasher · 22 February 2009, 16:15

You'll almost certainly be better off with the 90.

Ollyit on here runs a 5.4 with a 60, and although it goes OK I know he'd like more power.

Davybouy runs a 90 Tohatsu that gives him over 40Knts top end, and great fuel consumption.

I can't remember what Nos and Matt run on theirs but I'm sure they are 70s or 90s.

Nasher

doggypaddle · 22 February 2009, 16:30

Quote:

Originally Posted by Nasher

You'll almost certainly be better off with the 90.

Ollyit on here runs a 5.4 with a 60, and although it goes OK I know he'd like more power.

Davybouy runs a 90 Tohatsu that gives him over 40Knts top end, and great fuel consumption.

I can't remember what Nos and Matt run on theirs but I'm sure they are 70s or 90s.

Nasher

I have an 80, NOS 85, MATT 90, but all nice light yamaha 2 strokes.
Yam or tohatsu 2 stroke is the best for an SR IMHO.
the 60 would be OK but not a big foot, a bit un-inspiring in the performance dept.

no excuses · 22 February 2009, 18:19

I run a 90 yammi two stroke on mine and would not want less lol. I get 43-45 mph out of it with a 17" prop. Could run a 19" and pick up a few mph but realy like how it comes out of the hole with the 17". I would not want the weight of the merc 4stroke.

JSP · 22 February 2009, 18:37

There's a Yam 115hp on mine. But it isn't anywhere near as heavy as a 90 4 stroke.

tim2658 · 22 February 2009, 18:37

thanks for the fast replys i think i will look for something bigger just so im not to gutted when i open her up cheers tim

K&S · 22 February 2009, 18:43

Hi if it helps, I use a Avon 5.4 with a Mariner 60hp f/s standard gear box, flooding hull.
Any more than 3 people onboard and it does struggle to plane.
Would be a much nicer boat with say a 75hp 2 stroke

Nos4r2 · 22 February 2009, 19:06

We're using 85 and 90 2 stroke Yams.

Assuming you mean the 90EFI ,it's actually 6kg over the max transom weight of 175kg

Contact Avon and ask them if it's OK-but I wouldn't fit one anyway as the handling would be....err...interesting.

You'll be disappointed by a 60hp with more than one person aboard and a 4 stroke will be somewhat lacking in go.