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Old 06 February 2018, 14:41   #1
zip
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Which is faster?

A boat with a single 4 stroke 300HP or with twin 150HP 4 stroke?
Iím thinking with a single engine you probably drop some weight, so is it faster?
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Old 06 February 2018, 14:51   #2
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This isn't close.....single will be faster if it will get boat on plane.

Nothing to do with weight really but it helps, only 1 gearbox to push and more hp do with it, a much bigger prop turning at higher rpm.

Twins of 150hp is about a 200-225hp ish single performance wise.
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Old 06 February 2018, 16:13   #3
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This isn't close.....single will be faster if it will get boat on plane.

Nothing to do with weight really but it helps, only 1 gearbox to push and more hp do with it, a much bigger prop turning at higher rpm.

Twins of 150hp is about a 200-225hp ish single performance wise.
As above!

A 2nd like for like lump gives you about 30% higher speed, I heard once a third engine gives you just another 2% top end!!

Itís all about drag

However once youíve had twins itís hard to go back to a single, very versatile for many reasons
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Old 07 February 2018, 05:18   #4
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However once youíve had twins itís hard to go back to a single, very versatile for many reasons


Very true I miss mine
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Old 07 February 2018, 16:09   #5
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Thanks for your input gentlemen.
I’m researching my next sea going rib, and I think I’m going to go with a big monster outboard.
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Old 08 February 2018, 08:56   #6
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Put a 400R on it.

Single engine = less drag, less maintenance.

Twins is not really a requirement in the United States, due to our wonderful Towboat / Seatow coverage.
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Old 08 February 2018, 09:36   #7
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Yep, that is quite the monster motor.
If I go with another 730 or 733, I will probably stick with max rating of 300 HP.
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Old 08 February 2018, 17:31   #8
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Single all the way. I drive a boat with a single 300 Suzuki and handling and performance are so much better than twins.

I drive an abalone commercial boat with twin suzukis where I'm constantly working trim and trying to keep rpm equal. I also drive a gemini commercial dive rib for a friend from time to time with twin Yamahas which is also a pain compared to single. The extra weight on the back of the big gemini with divers onboard often means the back of the boat is constantly filling in a following sea at anchor.

Double the weight.
Double servicing costs.
Double the drag.
Etc etc etc.

All the boats I've been on with twins struggle to perform on just one engine, the offset mounting makes Them hard to get up on the plain. My mate recently did a gearbox on one of his twin 250 suzukis and had to limp home on one engine as the boat wouldn't plain on a single.
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Old 09 February 2018, 05:50   #9
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Single all the way. I drive a boat with a single 300 Suzuki and handling and performance are so much better than twins.

I drive an abalone commercial boat with twin suzukis where I'm constantly working trim and trying to keep rpm equal. I also drive a gemini commercial dive rib for a friend from time to time with twin Yamahas which is also a pain compared to single. The extra weight on the back of the big gemini with divers onboard often means the back of the boat is constantly filling in a following sea at anchor.

Double the weight.
Double servicing costs.
Double the drag.
Etc etc etc.

All the boats I've been on with twins struggle to perform on just one engine, the offset mounting makes Them hard to get up on the plain. My mate recently did a gearbox on one of his twin 250 suzukis and had to limp home on one engine as the boat wouldn't plain on a single.
Your mate wouldn't have got home at all with a single!! Lucky he had the redundancy of a second engine...........
I've run both singles and twins and would always choose twins over a single lump

Double the fun
Double the fun
Double the fun
Etc etc etc
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Old 09 February 2018, 10:15   #10
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I think for my application a big single is the best option.
Looks like Yamaha, Suzuki, Mercury, and Honda are my premier choices.
Not sure why Yamaha is so much higher in price though.
Suzuki is what I am leaning towards.
What you got?
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Old 09 February 2018, 10:36   #11
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On a Boat for that size Engine..Not only a lot faster..but more Nimble..Responsive ...and Better Handleing
Not to mention 1/2 the price to power..with big savings on Rigging..Fuel..and Servicing!
Some people do need twins..but not many.
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Old 11 February 2018, 03:32   #12
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Your mate wouldn't have got home at all with a single!! Lucky he had the redundancy of a second engine...........
I've run both singles and twins and would always choose twins over a single lump

Double the fun
Double the fun
Double the fun
Etc etc etc
No here we log on with marine rescue stating where we fish and plan to return home. He would of gotten home even if his radio and epirb failed as the rescue boat would of towed him home, or on of us ther boaties out there.

Most of the local charter boatsrun on single inboards, they also get a towif they break down.
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Old 11 February 2018, 03:46   #13
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No here we log on with marine rescue stating where we fish and plan to return home. He would of gotten home even if his radio and epirb failed as the rescue boat would of towed him home, or on of us ther boaties out there.

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Twins is not really a requirement in the United States, due to our wonderful Towboat / Seatow coverage.

Iím amazed at these attitudes. Yes even in the UK youíll likely get a tow to safety as well (although in some parts that could take a long time, and with no power and steerage it is at least an unpleasant wait and potentially dangerous).

A little bit of independence and self reliance is just good seaman ship. Iím not saying everyone should have twins, or even everyone should carry an aux (although if you are fitting 300hp you clearly have a big enough boat and budget to make it a serious consideration), but this reliance on someone else to bail you out as the first step to solving an engine problem is odd to me.
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Old 11 February 2018, 04:16   #14
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Iím amazed at these attitudes. Yes even in the UK youíll likely get a tow to safety as well (although in some parts that could take a long time, and with no power and steerage it is at least an unpleasant wait and potentially dangerous).

A little bit of independence and self reliance is just good seaman ship. Iím not saying everyone should have twins, or even everyone should carry an aux (although if you are fitting 300hp you clearly have a big enough boat and budget to make it a serious consideration), but this reliance on someone else to bail you out as the first step to solving an engine problem is odd to me.


Absolutely. Calling the cavalry is the last resort IMO & I'd count it as a personal failure.
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Old 11 February 2018, 10:34   #15
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Absolutely. Calling the cavalry is the last resort IMO & I'd count it as a personal failure.
Yep totally agree with this philosophy.
We blew a head gasket in the hard boat on a holiday in loch Crerran. limped back to largs on 1 engine at 7kts stopping off on the way, ok it was a different kind of boating but still stoped at some nice places and enjoyed the holiday rather than arranging a lift out and doing a repair miles from home.
The other thing is if your relying on a tow you don't know how competent the tow boat is and you risk damage if they get it wrong.
The RNLI almost wrote my daughter's racing dinghy off because of their rough handling cos someone on the shore thought they were in trouble.

There's a lot to be said for self sufficiency in an emergency
We carry an aux in our delta but my biggest worry is a breakdown miles from home and a)will the aux outboard get us home b)do we have enough fuel for it to get us home
It's also a pita to store
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Old 12 February 2018, 15:25   #16
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Agree completely.

Having run with a single 75hp merc 4 stroke for two summers in an area with no towboat service and minimal passers bye, I am going back to twins. Just bought twin 50hp hondas!

Boat will easily plane on one engine (hurricane 530) and the two BF50 are the same weight as the single merc (also save the weight of an aux motor!).

Redundancy, better holeshot, less draft, better stress distribution on transom.

don't see the downside aside from being 50% more expensive lol. hard to put a price on peace of mind though.

-M
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Old 13 February 2018, 08:13   #17
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Most of the local charter boatsrun on single inboards, they also get a towif they break down.
I'd have to say (from what I've seen) the opposite is the case here.

Most charter ribs I see on the west coast of Scotland are twin engined and most leisure ribs getting used offshore at least have an aux....so technically, twin engined.
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Old 13 February 2018, 08:20   #18
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............... I'm constantly working trim and trying to keep rpm equal. ........
Mercury "Smartcraft sync".......takes care of that for you.
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Old 13 February 2018, 09:34   #19
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I’m amazed at these attitudes. Yes even in the UK you’ll likely get a tow to safety as well (although in some parts that could take a long time, and with no power and steerage it is at least an unpleasant wait and potentially dangerous).

A little bit of independence and self reliance is just good seaman ship. I’m not saying everyone should have twins, or even everyone should carry an aux (although if you are fitting 300hp you clearly have a big enough boat and budget to make it a serious consideration), but this reliance on someone else to bail you out as the first step to solving an engine problem is odd to me.
There's very few rocky shores around here, most you'll beach on sand if you get pushed in. Minimal risk to safety.

Obviously, this changes a bit with each state.

South Carolina, I'll get stuck in the mud or an oyster bed before I hit rocks...

Seatow / Boat US tow coverage is only about $149 USD per year for the insurance, and they'll tow you up to 25 nautical miles offshore. All towing covered as part of the insurance. You usually get roadside trailer assistance too at no additional charge.
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Old 13 February 2018, 10:37   #20
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There's very few rocky shores around here, most you'll beach on sand if you get pushed in. Minimal risk to safety.

Obviously, this changes a bit with each state.

South Carolina, I'll get stuck in the mud or an oyster bed before I hit rocks...

Seatow / Boat US tow coverage is only about $149 USD per year for the insurance, and they'll tow you up to 25 nautical miles offshore. All towing covered as part of the insurance. You usually get roadside trailer assistance too at no additional charge.


I think you're missing the point, irregardless of the cost of a tow, it's a point of pride not to need it. Relying on someone else to get you out of the sh1t isn't the correct mindset for safe use of the sea......imo naturally.
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