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Twin Engines 60HP - 70HP 18FT Alloy Boat

Old 09-20-2019, 09:41 AM
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Default Twin Engines 60HP - 70HP 18FT Alloy Boat

I have decided to move forward with upgrading from my current Suzuki DF115 to a set of smaller twins.

Plan to keep the boat for the next 10 years so going to just jump right in.

My engines of choice have been narrowed down to either of these 4 Strokes:

2 x Yamaha 70HP
2 x Suzuki DF60AV (with high energy rotation).

The Yamaha gives me more HP without much of a weight increase so thatís a plus but are significantly more to purchase over the Suzukiís.

I am leaning towards the Suzukiís - with the lower end that has the gearbox better suited for heavier loads. Itís far cheaper and based on the 2000 hrs on my DF115 I have no concerns over reliability.

Can anyone chime in on in on anything I might be missing in selecting the Suzuki DF60AV over the Yamaha and the Suzuki standard DF60 ?

I donít care for going crazy fast, and my boat usage would be broken down into:

70% - Trolling offshore at 10-12MPH. Cruising at 20-25MPH

30% - Fully loaded taking family and friends out. I struggle getting on the plane with 7 adults and all the rest of the crap, so thinking the torque of 2 x DF60AVís might be the better choice for this?

Welcome any words of wisdom



Quintrex Legend 180




Last edited by shansgonefishin; 09-20-2019 at 01:19 PM.
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Old 09-20-2019, 12:15 PM
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I have a Yamaha F70, and it is fine, and I can't say anything bad about the Suzuki. Honda also makes a great 60, with a bigger prop.

I would make sure that the boat will be OK with the added weight.

Ho heavy is the boat?
Old 09-20-2019, 01:11 PM
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Originally Posted by Time Machine View Post
I have a Yamaha F70, and it is fine, and I can't say anything bad about the Suzuki. Honda also makes a great 60, with a bigger prop.

I would make sure that the boat will be OK with the added weight.

Ho heavy is the boat?
Thanks for the input.

Boat is a Quintrex Legend CC - around 1,400lb including everything I can think of... T Top, batteries, fuel etc etc (without people).

Max HP - 115
Recommended - 90

Other Weights:

Current engine DF115 - 410lb

DF60 - 229lbs (458lbs twins)
DF60AV - 265lb (530lb twins) Preferred option as of now
Yam 70HP 260lb (520lb twins)


.

Last edited by shansgonefishin; 09-20-2019 at 01:40 PM.
Old 09-20-2019, 04:09 PM
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From the picture, it looks like that boat is set up for a big motor, and a smaller motor to the starboard side.
Old 09-20-2019, 04:31 PM
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Originally Posted by Time Machine View Post
From the picture, it looks like that boat is set up for a big motor, and a smaller motor to the starboard side.
Yes. I run a 6hp DF6 kicker off of that little bracket I had welded on to the right of the DF115. The setup works well, except carrying the kicker in and out of an apartment up a good few steps every time I take it out.

That setup nearly killed me, long story!

Thats the quandary, just replace the 115 and be done with it, or go through a bunch of pain to modify the transom, change the rigging to duel controls etc. I think once that pain is over, the next 10 years should amount to an all round happy experience though - bloody hope so!!
Old 09-20-2019, 04:41 PM
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Why twins? Seems like a lot of additional expense and maintenance.
Old 09-20-2019, 04:57 PM
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Originally Posted by MacCTD View Post
Why twins? Seems like a lot of additional expense and maintenance.
Ultimately for redundancy. I have two tanks and will run each motors fuel independently. I had water in my fuel tank that killed the 115 and I unknowingly (lesson learned) put that same fuel into the kicker - during a squall. I was only a mile of the coast in the dark dead in the water. I know that no system is ever perfect but twins for me down here (Cayman Islands) is piece of mind.

Iíve done my own maintenance on the DF115 and really itís not that big a deal/cost so not too fussed about that
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Old 09-20-2019, 05:03 PM
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Those little quinnys aren't exactly over engineered. They're a light sheet alloy set up with marginal framing.

A twin set up would really be on the limits of they're engineered strength. I've seen an example that cracked and even warped the hull sheets because of a poorly set up trailer, hard use at maximum rec power. It ruined the boat, was fixed with portapower and extra framing and better trailer support.

Twin set on that hill would result in a stern heavy and poor weight distribution set up, let's face it, the hull weighs little more than a box of tissues.

Replace the single with another single or sell as is and buy a more substantial plate boat with full flotation pod if you're firm on twins.

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Old 09-20-2019, 06:36 PM
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Originally Posted by Gun smoke View Post
Those little quinnys aren't exactly over engineered. They're a light sheet alloy set up with marginal framing.

A twin set up would really be on the limits of they're engineered strength. I've seen an example that cracked and even warped the hull sheets because of a poorly set up trailer, hard use at maximum rec power. It ruined the boat, was fixed with portapower and extra framing and better trailer support.

Twin set on that hill would result in a stern heavy and poor weight distribution set up, let's face it, the hull weighs little more than a box of tissues.

Replace the single with another single or sell as is and buy a more substantial plate boat with full flotation pod if you're firm on twins.
Thanks for the feedback, exactly why Iím here.

For a ďbox of tissuesĒ type of hull itís been pretty good over the last 10 years, but I donít treat it like itís invincible or beat the shit out of it either. The trailer setup is fine. I have had a wave go through it once (took out my GoPro on the top of the windscreen) and amazingly all that water drained out thankfully very quickly. Definitely a freckle squeezing moment that. I know itís beside the point of the topic but I have confidence in the boat.

There is foam floatation under the transom, I believe they put that there intentionally to help with buoyancy for the Millennium Hulls with the increase in weight of the 4 strokes as they became more popular back in the early years (2003 Hull). I think an additional 100lbs (40 odd something kg) in the grand scheme shouldnít be too bad.

I have two batteries on the transom now that I could move forward if I really had to, and twins would probably match my current transom weight - if I moved the batteries forward... itís been that way for 10 years.

Thanks for the advise... appreciate it.


Last edited by shansgonefishin; 09-20-2019 at 06:47 PM.
Old 09-20-2019, 09:12 PM
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may not need the df60av as you are having twins. twins already means plenty of prop blade surface.

larger gearcase adds weight and drag, and i guess are needed when pushing a barge with a low top speed.
Old 09-20-2019, 09:27 PM
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Just came here to say that is the stumpiest looking boat I've ever seen.
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Old 09-20-2019, 09:31 PM
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Putting foam in a hull doesn't allow it to carry more weight, it makes it so that water can't fill it up. I would not go twins on that boat for the same reasons as above, it's a small, light, alloy boat.
Old 09-20-2019, 09:31 PM
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you'll need a 2nd 115 to plane out 7 people and gear.
Old 09-20-2019, 09:39 PM
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Originally Posted by Lookinup76 View Post
you'll need a 2nd 115 to plane out 7 people and gear.
We do get up with that load but it can be painful.
Old 09-20-2019, 09:40 PM
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Originally Posted by puppy View Post
may not need the df60av as you are having twins. twins already means plenty of prop blade surface.

larger gearcase adds weight and drag, and i guess are needed when pushing a barge with a low top speed.
This is the type of feedback Iím looking for, thank you.
Old 09-20-2019, 09:55 PM
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Originally Posted by brendanm View Post
Putting foam in a hull doesn't allow it to carry more weight, it makes it so that water can't fill it up. I would not go twins on that boat for the same reasons as above, it's a small, light, alloy boat.
Donít shoot the messenger.... from write-ups on the transom:

ĒMORE IMPROVEMENTS - All models (except for the 610s and 650s) now have Quintrex's "Maxi II" buoyancy-enhanced transomĒ

and another...

ďQuintrex calls its Maxi 2 transom. The intent of this innovation was largely aimed at four-stroke outboards, although it serves several purposes aside from providing additional aft buoyancy to support the weight of four-stroke motorsĒ
Old 09-20-2019, 10:11 PM
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Originally Posted by acme54321 View Post
Just came here to say that is the stumpiest looking boat I've ever seen.
Have to say Iíd love another few feet...
Old 09-20-2019, 10:27 PM
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Originally Posted by shansgonefishin View Post


Don’t shoot the messenger.... from write-ups on the transom:

”MORE IMPROVEMENTS - All models (except for the 610s and 650s) now have Quintrex's "Maxi II" buoyancy-enhanced transom”

and another...

“Quintrex calls its Maxi 2 transom. The intent of this innovation was largely aimed at four-stroke outboards, although it serves several purposes aside from providing additional aft buoyancy to support the weight of four-stroke motors”

Isn’t buoyancy a function of weight vs displacement? If you had AIR in the transom instead of FOAM, you would weigh less, displace the same amount of water and therefore sit higher in the water. Yea, you probably couldn’t measure the difference, but isn’t this how that works? I think these quotes are marketing.
Old 09-21-2019, 07:11 AM
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Originally Posted by proaudioguy View Post
Isnít buoyancy a function of weight vs displacement? If you had AIR in the transom instead of FOAM, you would weigh less, displace the same amount of water and therefore sit higher in the water. Yea, you probably couldnít measure the difference, but isnít this how that works? I think these quotes are marketing.
Itís definitely from the marketing dept, who knows, there is a lot of foam under the transom though.
Old 09-21-2019, 07:39 AM
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Upgrade to single 2 stroke 175 and make the 7 into a 1.....adding horsepower and tourqe while reducing weight and maintenance.

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