Sea Ranger Posted August 29, 2017 Share Posted August 29, 2017 Gday all Recently I've been looking at quite a few boats. Some of these have a common thread. Usually a 5 to 5.5 meter fiberglass boat that is rated at 150hp or more and they are sticking brand new 4 stroke 70hp , 80hp, 90hp engines on them. At the cost of a new motor for these old boats first why would you? and then second if you're going to spend 12 to 15k on a new motor why put such small donks on these boats? Any ideas? Bear Link to comment Share on other sites More sharing options...
Fishop Posted August 29, 2017 Share Posted August 29, 2017 Cheaper to run? I have a 100L fuel tank in my 5.6m fibreglass and a 90hp on the back. I did 5 half day fishing trips over the past month (approx 10-15km round trip each day = 50-75km total) went to fill up and only put 50L into the tank!! Not sure on what others get fuel economy wise with their bigger engines but 10-15 bucks a day seemed pretty good to me. Although that was only hitting up one or two spots a day, that included a little trolling as well!! Link to comment Share on other sites More sharing options...
PaddyT Posted August 29, 2017 Share Posted August 29, 2017 38 minutes ago, Fishop said: Cheaper to run? I have a 100L fuel tank in my 5.6m fibreglass and a 90hp on the back. I did 5 half day fishing trips over the past month (approx 10-15km round trip each day = 50-75km total) went to fill up and only put 50L into the tank!! Not sure on what others get fuel economy wise with their bigger engines but 10-15 bucks a day seemed pretty good to me. Although that was only hitting up one or two spots a day, that included a little trolling as well!! Underpowering your boat will lead to MORE fuel being used- you will constantly have to be on the throttle to keep it on the plane , spin the motor harder to get it on the plane etc.You will burn more fuel with a bigger engine if all you do is run flat stick all day but at sea that is close to impossible- I have a smaller boat that your with a 100Hp and would use slightly less than 1 lt per NAUTICAL MILE not KM which is about 1/2 the fuel you are using! Safety can also be a factor . As for why dealers do it- its because when they whack a "boat show special" or "package" together they can offer at a much lower price than a properly set up boat. Link to comment Share on other sites More sharing options...
browncrab Posted August 30, 2017 Share Posted August 30, 2017 I thought that boats aren't necessarily rated for hp of the outboard but more to do with the weight of the engine. The older boats are rated for 2 strokes so when upgrading to a 4 stroke they have to put on lower hp engine because 4 strokes are heavier than 2 strokes. Link to comment Share on other sites More sharing options...
jeffb5.8 Posted August 30, 2017 Share Posted August 30, 2017 As Browncrab said, They are rated to a Max HP & Max Weight So a 4 stroke can weight lots more than a 2 stroke although the 4 stroke motors are getting lighter now. My boat is Alloy 5.4mtrs and has a Max Hp of 130hp, I have the 115hp Etec on it and in a 4stroke the biggest I could have gone was the Suzuki 100hp. I don't feel my boats under powered with the 115hp, although I did see a guy with the same boat as mine and he had a 90hp Etec and he also said it went well. I can drag 3 adults on a ski tube and chase dolphins and cruise around Port Stevens swimming at different bays for 3.5 days from morning to afternoon and I used 83ltrs from the 90ltr tank. When I was looking there was a few boats with engines I felt were to small for the boat, they all tell you its fine but I have always felt its better to have closer to the Max Hp rather than the minimum. Boat Show specials are common for under powering, mine was a boat show special and I upgraded it to the 115hp from the 90hp. Link to comment Share on other sites More sharing options...
rickmarlin62 Posted August 30, 2017 Share Posted August 30, 2017 the trend to put smaller 4st motors is definitely because of the weight difference...the four strokes develop a different power curve to the 2st motors...a mid range 4st will get the hull on the plane and hold it on the plane at lower speeds than the same size 2st as they develop their power at higher revs...when I looked ar repowering my vsea I had to work out power/weight/fuel consumption to suit my hull..i had a 60yammie 2st.same weight as 70 2st..if I went to a 704st I would have added thirty kilo..no more power no more speed only better consumption...I went 90hp 2st..12 kilo heavier.but massive gain in usable power...jurys still out on consumption as I havnt been for decent trip yet but im thinking same or only slightly more as I use heaps less revs now to do a comfortable cruise speed...it leaps out of the hole and doesn't die off the plane on the back of swells in a working sea.....horses for courses is the old saying....my mate just repowered with 135 yammie 2st..he saved $6800 on the 4st he was looking at....that's a lot of fuel you can buy for that saving...if you find a good hull you like try it on the water and see how it performs with the motor that seems underpowered..it may suit your needs...rick Link to comment Share on other sites More sharing options...
Fishop Posted August 30, 2017 Share Posted August 30, 2017 5 hours ago, PaddyT said: Underpowering your boat will lead to MORE fuel being used- you will constantly have to be on the throttle to keep it on the plane , spin the motor harder to get it on the plane etc.You will burn more fuel with a bigger engine if all you do is run flat stick all day but at sea that is close to impossible- I have a smaller boat that your with a 100Hp and would use slightly less than 1 lt per NAUTICAL MILE not KM which is about 1/2 the fuel you are using! Safety can also be a factor . As for why dealers do it- its because when they whack a "boat show special" or "package" together they can offer at a much lower price than a properly set up boat. Ill have to do a bigger trip and fill up before and after to work it out properly. Problem with doing heaps of small trips and having a big fuel tank I only fill it up once every 4-6 weeks! Link to comment Share on other sites More sharing options...
zmk1962 Posted August 30, 2017 Share Posted August 30, 2017 (edited) Is there a trend to underpower ? ....hmmm have a look at the attached photo taken at the recent Sydney Boat show. The craft was around 8m with a 3m beam...and on the back a single 150HP 4st. When I asked the rep there if he thought it was maybe a tad underpowered he went into a lengthy dialog about infusion resin manufacturing process ensuring just the right amount of resin resulting in minimal weight hulls .....( yerrr right - me thinks - having faced many a green wave offshore and been very glad that I had 200hp on my 6.35m with 2.4m beam hull and that Haines had overspec'd and laid that 1in think fibreglass at the bow and stern).... Fact is... if the vendors can cut costs they will... beware the boat show / boat yard specials. Cheers Zoran Edited August 30, 2017 by zmk1962 correct error Link to comment Share on other sites More sharing options...
Fab1 Posted August 30, 2017 Share Posted August 30, 2017 1 hour ago, zmk1962 said: Is there a trend to underpower ? ....hmmm have a look at the attached photo taken at the recent Sydney Boat show. The craft was around 8m with a 3m beam...and on the back a single 150HP 4st. When I asked the rep there if he thought it was maybe a tad underpowered he went into a lengthy dialog about infusion resin manufacturing process ensuring just the right amount of resin resulting in minimal weight hulls .....( yerrr right - me thinks - having faced many a green wave offshore and been very glad that I had 200hp on my 6.35m with 2.4m beam hull and that Haines had overspec'd and laid that 1in think fibreglass at the bow and stern).... Fact is... if the vendors can cut costs they will... beware the boat show / boat yard specials. Cheers Zoran You are a smart man Zoran.There's plenty of gullible people that attend these sorts of shows and fall for the sales pitch of the salesman.They know that for every fish missed there's plenty more to be caught.Its the same at any shop,car dealers etc.They are there to tell you what you want to hear to make a sale and are always your best mate for those few moments before the sale.After the sale it's usually Asta la vista with the after sales service.etc. Having said I'm noticing more and more of those people that believe anything they hear and are led along like sheep so nothing will change. Link to comment Share on other sites More sharing options...
Guest Guest123456789 Posted August 30, 2017 Share Posted August 30, 2017 1 hour ago, Fab1 said: You are a smart man Zoran.There's plenty of gullible people that attend these sorts of shows and fall for the sales pitch of the salesman.They know that for every fish missed there's plenty more to be caught.Its the same at any shop,car dealers etc.They are there to tell you what you want to hear to make a sale and are always your best mate for those few moments before the sale.After the sale it's usually Asta la vista with the after sales service.etc. Having said I'm noticing more and more of those people that believe anything they hear and are led along like sheep so nothing will change. +1 a lot of it is driven by manufacturers/dealers wanting to keep costs low in my opinion. Smaller engine means lower weight and less speed - think about what that means for hull warranty claims. Link to comment Share on other sites More sharing options...
Trailcraft43 Posted August 30, 2017 Share Posted August 30, 2017 Your right on the money Zoran. i totally agree. Link to comment Share on other sites More sharing options...
PaddyT Posted August 30, 2017 Share Posted August 30, 2017 13 hours ago, flatheadluke said: +1 a lot of it is driven by manufacturers/dealers wanting to keep costs low in my opinion. Smaller engine means lower weight and less speed - think about what that means for hull warranty claims. Unfortunately Luke, in general manufacturers have very little say as to what goes on the back of their hulls, most good builders tend to be horrified by underpowered boats as usually what happens is the customer starts blaming the hull for its poor performance. Dealers are the ones mainly responsible plus the general attitude of the buying public thinking that they are getting a great deal! Most builders I have spoken to about hull warranty claims reckon that 99% of problems are due to poor trailer set ups anyway- again the dealer cutting corners or not knowing their job. Its not easy for the newbie boat buyer out in the marketplace Link to comment Share on other sites More sharing options...
JonD Posted August 31, 2017 Share Posted August 31, 2017 Every boat I've ever owned seemed underpowered to me, just wish they would put the max rather than the recommended hp. I suppose if I wanted to waiste money and buy new I could go bigger. Ive seen some figures on the latest 200 Yamaha 4 stroke where it actually outperforms my 70 Yam 4stroke simply because it can sit on 3500rpm on a 6m boat doing 50kmh where I have to crank up to 5800 rpm to do that speed on my little 315kg rib and burn more fuel. According to my wife who knows almost everything "bigger is better" I think she puts me in the underperforming engine category!!!!! Link to comment Share on other sites More sharing options...
sydney south Posted August 31, 2017 Share Posted August 31, 2017 (edited) I have always been happy with the recommend HP or just over. The boats that I have owned with the max HP fitted. Never seem to sit well at sea. As they are generally bum heavy. Edited August 31, 2017 by sydney south Link to comment Share on other sites More sharing options...
jeffb5.8 Posted August 31, 2017 Share Posted August 31, 2017 Picked up on my new tow car today, might be slightly over powered to tow my little boat. Link to comment Share on other sites More sharing options...
zmk1962 Posted August 31, 2017 Share Posted August 31, 2017 Ha ha ha. Awesome !!! What top speed do you get out of the tinny on the 9in training wheels? Cheers Zoran Link to comment Share on other sites More sharing options...
Trailcraft43 Posted August 31, 2017 Share Posted August 31, 2017 Haha, first to the boat ramp in the mornings. thats always a plus.? Link to comment Share on other sites More sharing options...
jeffb5.8 Posted September 1, 2017 Share Posted September 1, 2017 15 hours ago, zmk1962 said: Ha ha ha. Awesome !!! What top speed do you get out of the tinny on the 9in training wheels? Cheers Zoran Cost a fortune a quick trip costs $80 in fuel ($65 for the car and $15 for the boat) Link to comment Share on other sites More sharing options...
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