AvonSearider 5.4 outboard/transom size

Brandy Bluff · 04 June 2006, 18:45

2 years ago I bought an Avon Searider 5.4m with twin 30hp johnson, 20 inch shafts, 10 x 15 props. Boat and motors are 1987, both are in very good condition.
Attached are pitchures. Is the seat arrangement and transom original? How about the transom height? Top of transom to keel is 25 inches. At the Transom the aluminium sleeve goes over both sides and is thru bolted. We use the boat for family fun (waterski, tube, kneeboard, cruising). Pulling a teenage out of the water on waterskis works but, she's working hard coming out of the hole.
Once she has dumped her water and shes on a plane I have to reduce throttle. I was told she was clocked at 35mph which I can believe once on a plane. I'm not happy with her start off performance. Great boat otherwise. Safe boat. Cool boat.
The Johnson/Evinrude shop up the road has a 1987 rebuilt 70hp johnson and a 1993 60 hp johnson both are 20 inch shaft. He said we could cut down the transom???
Now knowing our usage for this boat how should the outboard be configured? Because of cost I'll be leaning towards used.
Ribs are not popular around here so I can't get much local feedback.
I'd appreatiate any feedback.

Nos4r2 · 04 June 2006, 22:08

The seating arrangements/dashboard are original but the transom plate isn't.

You can cut down the transom but it'll need sealing properly-the early seariders are ply cored hulls. Probably better to get the right shaft length engine.

It looks in exceptionally good condition for the age!

Brandy Bluff · 05 June 2006, 01:07

The hull was like new, there wasn't even a scratch. I don't think it ever caught sight of the sea bottom.
Would the original transom have been 25 inches high (straight across) or would it have dropped down and 20 inches high?
What kind of power should I go with?

dctucker · 05 June 2006, 20:28

I'd go for the single 70 Johnson. I have a 5.4 with a 1980 Merc 80 hp, with a 13.5 x 21 stainless Michigan prop. I also have Nauticus SmarTabs. It's a nice combination when the old Merc is running well (I have some intermittent issues that have led me to beleive I need to replace the electronic ignition). It's pretty much instant planing when you jam the throttle forward, even while the hull drains. I can even get 2500-3500 pound keelboats planing behind me.

I'd also recommend that you look a new Tohatsu TLDI, 70 or 90 (same motor, but for the ECU). I think it's the best all around value in a new outboard for the boat. I think they can be had for as little as $7500 USD. Yes, that'a a lot more than a used, but I suspect you may make it up in maintainence and repairs and fuel economy in just a few years.

Brandy Bluff · 05 June 2006, 20:48

dctucker,
I see you also have a 5.4 Searider, is your Merc 80 a 20 inch shaft? Are you mounted directly onto the Plywood fiberglass transom or is there a metal mounting plate?
How would the fuel consumption compare between a 70hp and 2x 30hp?

Biggles · 05 June 2006, 21:44

Amongst other things talked about on this thread some how I find the fact that our North American cousins are considering fuel costs very reassuring.

118118 · 05 June 2006, 22:40

i reckon, if you were to take the stainless plate off, there would be the standard cutout for a normal longshaft outboard.

the stainless is probably only there to fill in the cutout. see where there could be a cutout underneath the stainless in this pic http://www.boatsandoutboards.co.uk/view/F101198/

im not sure im right, but iv never seen a 5.4 without this cutout.

good luck with your boat!

dctucker · 06 June 2006, 15:15

Quote:

Originally Posted by Brandy Bluff

dctucker,
I see you also have a 5.4 Searider, is your Merc 80 a 20 inch shaft? Are you mounted directly onto the Plywood fiberglass transom or is there a metal mounting plate?
How would the fuel consumption compare between a 70hp and 2x 30hp?

As I recall, it is a 20" shaft, mounted directly to the stock transom as shown in the link posted by 118118.

Economy-wise, any new-tech 2-stroke or 4 stroke will kick the pants of the old carbed 2-strokes in either case. I really have no idea if the 1x80 or 2x30 will provide better economy. I think you could shut down one of the 30's for low speed travel and save some fuel...

I just spent a couple of days coaching in my boat, and in very mixed use (lots of idling and low speed driving, with some brief high speed bursts), I used ~6 US gal/day. I'm thinking about how many days I'll be doing that in the next couple of years, and it's got me thinking about repowering with a modern 2-stroke...

Anyone have any sense of the improvement in economy for a 75 or 90 TLDI or e-tec or such, vs a like carbed 2-stroke?

Brandy Bluff · 15 June 2006, 16:51

I would like to thank those who shed some light onto this topic. Its a great forum you have going here.
Also for those who are interested I emailed AVon Uk and here was their reply,

"the boat was not fitted with that transom plate when it left Avon.
it started life as a single engine version, with a cut-out in the transom, then somebody converted it to a twin engine transom.

If you could get that plate off, I think that you would find the cut-out
underneath.

What you would have to make sure of, is that the top of the transom is
plated or sealed to prevent ingress of water into the ply of the transom.

Regarding how quickly the water exits the ballast chamber, a 70HP would
push it out quicker than a 40HP but anything 60HP or above shouldn't have any problem getting up onto the plane quickly."

So now my intension will be to remove the metal sleeve and plan for a single outboard 20 inch shaft at least 70hp. (I like the idea of keeping a tall transom to help avoid ingress of wave when stopping quickly) I say at least 70 hp because I've learn't from this forum its all about speed!!!
When I read the postings and view the pic's, its Big Motors and how can I get a couple more knots!!
By the way, in your pic's do you guys ever get to go boating in the sunshine?
People always have jackets on. Around here our waterways are quiet if its not sunny and warm.
To respond to a post by Biggles yes Fuel consumption is an issue here now, especially since last summer when gas/diesel hit $1.35cdn/ltr. Its down to $1.13cdn/ltr now but soon it will probably start its way up when people start travelling on summer vacation.
This is why I find it humorus to see your pics with big honkin motors strapped to the back side of these relatively light boats skimmin along the water. I thought fuel(petrol) was expensive in the UK. I guess when it comes to men and speed we can't give up everything!!
Informative forum keep it up.