Best engine size?

cinman2003 · 21 July 2006, 20:10

I am currently doing some research around buying my first Rib, and have narrowed down to a few. Current preference is an Avon Searider 4m, with a jockey console and about 40hp engine. I want to use in the Solent, crossing to IOW and back, and probably pull some toys at some stage. I'm reasonably heavy (around 15.5stone) and would appreciate advice on an engine size that would suit?

Biggles · 21 July 2006, 20:31

Hi Cinman,

My friend has that setup with a 40 HP Yamaha 2 stroke on the back and its awesome. He doesn't weigh 15.5 stone though. I run a 50 HP Yam 4 stroke which pushes the boat along nicely. I weigh 13.5 stone and carry passengers at times.
I think 30 HP is to small. I've seen Seariders with 30s on the back and they are a bit lame.
A good 40 should do, not 4 stroke at that size tho. You probably need a 50 for 4 stroke.
In my honest opinion and I'll probably get flack for saying this. Steer clear of the Honda engines in this size.
Best of luck with your new purchase. You won't go far wrong with a Searider. I even got back from the IOW last week in Force 6/7. It just takes a little time and some patience to read the waves.

Regards Nick R.

Nos4r2 · 21 July 2006, 21:59

I'm with Biggles on this.

I've got a 50hp 2-stroke on mine and it's wonderful-no trouble apart from being a tad uncomfortable 3 up (and I'm HEAVY!) in force 7 gusting 8 out in Poole Bay.I wouldn't have wanted the extra weight of a 4-stroke in those conditions with effectively 4 people on board.

It's considerably more expensive to run a 2 stroke though. If you don't plan on doing silly things in it then its not going to be a problem having the extra weight of a 4-stroke and your wallet will feel much better after filling up.

ian parkes · 22 July 2006, 00:50

why steer clear of a honda 50 its the best and lightest 4 stroke in its class , a whole 7 kg heavier than a yam 50 2 stroke . The fact that you need to carry less fuel and no oil actually make the load considerably lighter unless you are only going out for an hour or so .

Biggles · 22 July 2006, 08:49

Ian,

Fair comment. I don't own a Honda but I've been out with a couple and they just don't seem to have the same power output as other engines. Maybe they were just set up wrong with the incorrect propellor etc.

What was good to see last week was my friends Searider with a newish mariner 50 HP 2 stroke, two adults on board and fifity litres of fuel doing 34 Knots back from Nab Tower. He lost me anyway. He managed to do that because he went to Pepes and sought advice on a new propellor. I really need a new propellor, but I'm selling the boat this winter, as I am only getting 5100 revs max on my 15 incher but that will give me 32 Knots on a good day. It sups petrol at that speed though.

Because I always go out with that Mariner I know that my fuel consumption is exactly half of his. That is a major factor to take in to consideration on any engine purchase I should imagine. Certainly something for Cinman2003 to consider.

If I can afford it on my next boat purchase over the winter I shall be getting a four stroke.

This is all information for Cinman to make an educated purchasing decision from.

fast fred · 22 July 2006, 10:22

2stroke 40-50hp outboards have been around for a long time and have not changed much, Proven relieability. 4strokes,good for recalles,thay still need some sortin time.

ian parkes · 22 July 2006, 11:20

Quote:

Originally Posted by fast fred

2stroke 40-50hp outboards have been around for a long time and have not changed much, Proven relieability. 4strokes,good for recalles,thay still need some sortin time.

I constantly read comments like this and it doesn't make sense . Iam not geting into the 4/2 stroke debate here but you can't generalise about anything like that . One make of four stroke may be heavy and problematic and the other no problem at all .
You need to choose the best engine in a certain size , while honda make the lightest 50 they may make the heaviest 90 . It seems to depend on what HP they use that particular engine for ie the honda is probably a 40 or 50 in the same engine as is the 15/20 . I don't see the point in buying the lower power model .
Fuel consumption has for me to be the biggest factor and although I have limited knowlege I looked for the biggest engine I could find for the given boat size working on the theory that it wouldn't be working hard when cruising .
All I can say is the Valaint 490 and suzuki df 70 I ended up with seem very good on both fuel and power/weight ratio Iam getting about 1/2 litre to a mile .

Mollers · 22 July 2006, 11:38

Quote:

Originally Posted by ian parkes

I constantly read comments like this and it doesn't make sense . Iam not geting into the 4/2 stroke debate here but you can't generalise about anything like that . One make of four stroke may be heavy and problematic and the other no problem at all .
You need to choose the best engine in a certain size , while honda make the lightest 50 they may make the heaviest 90 . It seems to depend on what HP they use that particular engine for ie the honda is probably a 40 or 50 in the same engine as is the 15/20 . I don't see the point in buying the lower power model .
Fuel consumption has for me to be the biggest factor and although I have limited knowlege I looked for the biggest engine I could find for the given boat size working on the theory that it wouldn't be working hard when cruising .
All I can say is the Valaint 490 and suzuki df 70 I ended up with seem very good on both fuel and power/weight ratio Iam getting about 1/2 litre to a mile .

Yes, but us Cornish ribbers are all fit and lithe. The Solent guys appear to be mostly over 15stone Ian.

fast fred · 22 July 2006, 11:38

"I constantly read comments like this and it doesn't make sense "
just what dosesn't make sense? 4strokers don't work twice as hard to make the same power, which in turn thay ware an the same rate, or that thay have about twice the movein parts to fail in the powerhead.
simplicity is key.

Mollers · 22 July 2006, 11:50

Quote:

Originally Posted by fast fred

"I constantly read comments like this and it doesn't make sense "
just what dosesn't make sense? 4strokers don't work twice as hard to make the same power, which in turn thay ware an the same rate, or that thay have about twice the movein parts to fail in the powerhead.
simplicity is key.

If you're a Yank. I don't think that Messers Honda,Yamaha, Suzuki, et all would agree with that. I understand what you're saying, I just think that that view is a little out-dated. You must bear in mind that gas is $8 ish a gal here, so economy is a huge factor when engine choices are made. So the 4strokes failings are more than made up for in the improved economy.

ian parkes · 22 July 2006, 12:14

as i said I wasn't trying to start another 2/4 stroke debate and which was the best . Just that these days nobody makes a crap engine or machine , be it car bike or boat engine , so the riliability issue isn't really a reason for choice .

Fred if you look closer at the workings of a 2 stroke your reasons for a 2 stroke lasting longer will no longer make sense , its proven in practice that 2 strokes have a much shorter life , but that is a different debate to the one here

Mollers you had better hope us 15 stone plus ribbers don't sit on you , anyway did you ever see a thin seal , iam fat for a reason

fast fred · 22 July 2006, 12:31

well, i guess I'm a YANK,we came form over thare at one time.
anywho, you would need to make your prioritis known, if fuel is important, relieability, speed ect.

the gas for my wee hull is 10bucks a gal, you can't buy it at a pump, it's shipped by drum to my shop, a 1/2 lt would not be enuff to fire it, it's 820cc's.
she'll rip through 12-14 gals an hr at WOT.

if she didn't pull so much fuel i would for sure take it out more, could reset it up to pull less fuel, but then i would be crapin on my prioritys and she would be far less fun..... for me.

fast fred · 22 July 2006, 12:44

"Fred if you look closer at the workings of a 2 stroke your reasons for a 2 stroke lasting longer will no longer make sense"

be buildin 2stroke for over 20yrs now, got some out thare ( all over the planet) that have been runnin longer than four strokes have been on the market, and still run like a top. thinkin i got the 2 stroke stuff down.

eupa · 23 July 2006, 13:33

go with Fast Fred on this one ( what a fantasic, original, sexy username??)

The resaon is very siimle- there are much, much fewer moving parts on a 2t than a 4t. And nowdays a sophisticated 2t HPDI will turn out lower fuel consumption than the equivalent 4t.

Fred 10 bucks a US gal... that's robbery . whether is drummed or not.

Jonathan

eupa · 23 July 2006, 13:47

she'll rip through 12-14 gals an hr at WOT.

That's outragious!!!!!!!!!!!!

being doing some serious testing recently on my yams:: here goes- will use the same units as you.

-- two x 250 3470 c.c yams HPDI

cruising at 4000 rpm - 39 kts 17 usgals/hr -( measured floscan 550)
WOT 5300 rpm 50 kts 21 us gals/hr
comfortable 3200 rpm 29 kts 10 us gals/hr

Same parmeters for all figures. with 23" props Michigan wheel , rapture SS
Boat weighs in at 2200 kgs dry.

FIGURES ARE FOR TOTAL CONSUMPTION ( i, both engines)

1 us gal= 3.87 litters

jonathan

fast fred · 24 July 2006, 13:09

the paramiter of the outboard i run are differant than the outboards in your test, set up so to meet the prioritys of it's owner.

if your 250's were set up the same you would see similler fuel consumption,
thay would also be twin 350+hp @ 8250rpm.

can't beat how quiet them 4strokers are.

fast fred · 24 July 2006, 15:11

"That's outragious!!!!!!!!!!!!"

just wanted to say, thare are guys that got two ,three,even four SC1400hp
inboards in thare hull, thay eat more $$ in cheapper fuel than i can carry,
just gettin on plain.
my hull is a small fish, speedy fish.

kowached · 25 July 2006, 19:30

Cinman, just thought I'd add my $0.02.

When selecting your engine, see what other engines the Manufacturer makes that use the same lower unit and similar powerhead. For example, my Nissan 40hp is basically identical to the Nissan 50hp, which means that I can have an extra 10hp with NO weight penalty (they both weight 147lbs). You can bet that when it comes time to rebuild my 40hp, I'll be looking to install a 50hp powerhead.

ian parkes · 25 July 2006, 19:42

Quote:

Originally Posted by kowached

Cinman, just thought I'd add my $0.02.

When selecting your engine, see what other engines the Manufacturer makes that use the same lower unit and similar powerhead. For example, my Nissan 40hp is basically identical to the Nissan 50hp, which means that I can have an extra 10hp with NO weight penalty (they both weight 147lbs). You can bet that when it comes time to rebuild my 40hp, I'll be looking to install a 50hp powerhead.

I don't understand why all the manufacturers do this .
I know the Honda 20 I had was identical to the 15 exept it revved a bit higher . The bit i can't undrestand is how much more the higher power option often costs .

Biggles · 25 July 2006, 20:09

Going back a few years when I was in to motorbikes all my mates used to get their cylinder bores skimmed and put oversize piston rings on. This used to give them more HP. Doesn't anyone do that in the boat world ?