1974 CURRITUCK 16 Re-power

Optimizing the performance of Boston Whaler boats
Braco
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1974 CURRITUCK 16 Re-power

Postby Braco » Thu Aug 11, 2022 12:10 pm

I have a 1974 16-footer that was a CURRITUCK but is now a bare hull that I plan to re-power. I believe that a 16-foot hull is weight sensitive. I believe these c.1970 16-foot hulls are rough-riding boats. [In selecting an engine the boat's] top speed is not my concern. In my normal use of the boat there will only be aboard just my wife and I. But I want the boat to have the ability
  • to take out a two friends
  • to get on plane easily
  • to safely operate in the ocean and in currents and on waves, and
  • to able to boat camp on coastal islands with more gear aboard than a typical day trip.
Engine options I will consider:
  • Suzuki DF90 at 343-lbs and $11,000
  • Yamaha F70 at 253-lbs and $12,000 to $13,000
  • SUZUKI DF60A at 250-lbs, and probably cheaper than the others but I do not have a price
For re-powering this 1974 16-foot bare hull I have am leaning toward a Yamaha [F70] for its [low] weight. I know [a Yamaha F70] is a solid engine].

I’ve become interested in the DF60AV. I have only found one other testimonial on this engine. I worry the DF60AV won’t have the power to handle navigating open water and river mouths.

Q1: can low gearing and the correct propeller make up for lack of horsepower at low to middle engine speeds?

Give my your first-hand experience with these three engines on older hulls

BACKSTORY: I have recently picked up a 1974 16-foot hull. The previous owner is a charter boat operator and a marine surveyor. He restores boats in the off season. He acquired the hull and started the restore in c.2020 thing that the pandemic would cause is charter business would be slow or shut down, unexpectedly he was he was busier with charters than ever before. He replaced the transom and did the majority of exterior hull repairs. Still lots of work to do on the interior hull.

On another boat, not the 16-footer but a 13-footer, I used a SUZUKI DF30 due to its weight and good reviews from friends. I have enjoyed the Suzuki and the dealer so far.

According to Boston Whaler this hull was outfitted as a Currituck. At this point the hull is bare and the only included hardware was the lifting rings and Norman pin. I already have a 1966 13-footer that I restored and kept classic style, with a blue interior, side console, and mahogany. Because this 16-footer has no interior included, I plan to make it more of a custom with a stand up console, a leaning post, and no wood. The batteries will be in the console, and a 22-gallon Moeller fuel tank will be under the leaning post. I would like to have a rear bench in front of the engine, and maybe a SAKONNET-style forward platform for storage and a lounge area.

I live in Biddeford, Maine. I will use the boat to explore around coastal Maine and trailer to the lakes region on occasion.


ASIDE: I know the re-power topic has [discussed at length--please do not use figures of speech that refer to violence], but after searching around I haven’t found a ton of recent information.

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Phil T
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Re: 1974 CURRITUCK 16 Re-power

Postby Phil T » Thu Aug 11, 2022 12:19 pm

From my 20 years of participation on three Boston Whaler-oriented forums, my advice is to repower with the Yamaha F70. It has the best power-to-weight ratio. It is a reliable engine and installed on hundreds of Boston Whaler boats.

When re-powering [the engine choice] is not always top speed, [the engine choice] is also about displacement and torque. When you add passengers and gear, you need the boat to be able to get up on plane and maintain speed.

Price out the Suzuki DF60. Re-powers are expensive, and you don't get your money back.

Purchase what you can afford and live with.
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jimh
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Re: 1974 CURRITUCK 16 Re-power

Postby jimh » Thu Aug 11, 2022 1:26 pm

ASIDE:
Braco wrote:ASIDE: I know the re-power topic has been [previously discussed]...but after searching around I haven’t found a ton of recent information.
I don't know what your criterion was for recent. The Boston Whaler boats being re-powered that are discussed in these forums are often boats that are 15 to 50-years old, so the boats are not changing. Advice about re-powering them has not drastically changed in the "recent" past, that is, in the last six months.

I don't know your criterion for "a ton" of information. There a thousand threads about re-powering older Boston Whaler boats in the archives, many of them on 16-foot hulls.

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Re: 1974 CURRITUCK 16 Re-power

Postby jimh » Thu Aug 11, 2022 1:31 pm

If weight is a primary concern then the Yamaha F70 at only 253-lbs is the best fit for that criterion and also for your other criterion of having reserve power. Good luck finding an F70 engine available, as long lead times have been reported for them.

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Re: 1974 CURRITUCK 16 Re-power

Postby jimh » Thu Aug 11, 2022 1:38 pm

Braco wrote:Q1: can low gearing and the correct propeller make up for lack of horsepower at low to middle engine speeds?
With proper propeller selection a 60-HP engine can get a 16-footer on plane and maintain it on plane without much trouble. You might be interested in these comments about engine weight on the classic 16-foot hull at

Storm Story: July 17, 2006, Manitoulin Island
https://continuouswave.com/ubb/Forum1/HTML/013113.html

Boat speed requires horsepower, so rigging with a 60-HP won't push the boat at full-throttle as fast as a 90-HP.

Estimated speeds for various engine horsepower on a classic MONTAUK are given at

https://continuouswave.com/whaler/refer ... power.html

While the hull you have is still bare, you should weigh the hull. Compare the weight of your hull to the weights listed in the REFERENCE article on the 16/17 foot hull at

https://continuouswave.com/whaler/reference/16-17/

Braco
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Re: 1974 CURRITUCK 16 Re-power

Postby Braco » Thu Aug 11, 2022 4:01 pm

Phil T wrote:...my advice is the Yamaha F70. It has the best power-to-weight ratio. It is a reliable engine and installed on hundreds of Boston Whaler boats.
Thanks for the advice. The Yamaha F70 seems like the obvious choice.

I am aware I won’t get my money back [from the cost of buying a new engine to re-power a 48-year-old bare hull Boston Whaler boat that needs work].

After re-powering my 13-footer with a modern engine, I would have trouble going back to a used engine with potential problems. Having a modern outboard engine has been so enjoyable: it gives instant starts and quiet and smooth operation.

Duckmanreno
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Re: 1974 CURRITUCK 16 Re-power

Postby Duckmanreno » Sat Aug 13, 2022 8:47 pm

I have a 1974 MONTAUK 17 that was re-powered with a new F70 Yamaha in January 2022. I am very happy with the Yamaha F70 engine for these reasons
  • instant starting
  • good fuel efficiency
  • runs at low engine speeds for hours without a hiccup
  • looks like it belongs on the boat, and
  • is a good fit for the boat.
The Yamaha F70 took six months to be delivered after I placed my order.

[When buying a new outboard engine I recommend comparing] prices from a few dealers.
1974 Montuak
2021 Yamaha F70

jimh
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Re: 1974 CURRITUCK 16 Re-power

Postby jimh » Sun Aug 14, 2022 8:41 am

Duckmanreno wrote:I am very happy with the Yamaha F70 engine for these reasons
  • instant starting
  • good fuel efficiency
  • runs at low engine speeds for hours without a hiccup
  • looks like it belongs on the boat, and
  • is a good fit for the boat
All modern outboard engines will exhibit rapid starting, very improved fuel economy compared to legacy outboard engines using simple carburetor fuel induction and two-stroke-power-cycle technology, and will run well and endlessly at low speeds. I don't think the Yamaha F70 has any exclusivity on those parameters.

How a modern outboard engine will look on the boat is subjective, but in general I think older boats will benefit from an engine whose cowling size is not extraordinarily large compared to its horsepower.

The "fit" on a boat--the boat in this case is about 50-years-old--is probably mostly about engine weight on the transom, with less weight being better, and particularly so in the case of smaller boats where the engine weight will be a large percentage of the total bare hull weight. In that regard because of its very modest engine weight the Yamaha F70 does stand out somewhat from competitors.

Duckmanreno wrote:The Yamaha F70 took six months to be delivered after I placed my order.
Thanks for mentioning the waiting period, as it could have a significant effect on the decision of what engine to buy. For some boaters, six months might be an eternity to wait. Availability of modern outboard engines now has become an element in the purchasing decision process.

Braco
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Re: 1974 CURRITUCK 16 Re-power

Postby Braco » Sat Aug 20, 2022 3:22 pm

Thank you all for the replies. I have narrowed my search to two engines.

--a Yamaha F70 $10,500 to $13,000 rigged and installed depending on dealer.

-- a Suzuki DF60av with big gear case version. $9,000 rigged and installed

I definitely think the Yamaha f70 is a solid choice for my needs. I have also found a few dealers in New Hampshire and Maine with the Yamaha F70 engine in stock. I have no experience with the Yamaha dealer that has the best deal on the F70. The price difference between dealers seems like large. Multiple dealers said $10,000 for the loose engine, but one says $8,500.

I bought an engine from the Suzuki dealer in c,2020, and I have enjoyed working with them. He has a regular DF60 in stock but would have to order the AV high-thrust version with a six to eight month lead time. [A six to eight month lead time is not] a big deal as I have lots of work to do on the hull. After reading some accounts on this forum and others I have decided that the regular 60-HP is probably not enough power for my needs. My biggest concern is long time to plane and having the boat struggle to accelerate to plane with a bit of load.

Am I correct in thinking that a high-thrust 60-HP would provide [acceleration onto plane at full throttle from a standing start] and low-speed to mid-speed cruising that would be comparable to the Yamaha F70, but with ultimate full-throttle boat speed lower?

I am curious about the DF60 engine because of the price difference and the trusted Suzuki dealer/

I am also willing to spend a little more if the Yamaha F70 seems to really be the superior option. The F70 engines are certainly a proven choice.

I have found this prior discussion on thee Suzuki DF60av at https://continuouswave.com/forum/viewtopic.php?t=3075

I greatly appreciate all of your advice and expertise.

Caleb

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Re: 1974 CURRITUCK 16 Re-power

Postby jimh » Sat Aug 20, 2022 9:03 pm

Based on the quotes you cited the Yamaha F70 engine is certainly being sold at a significant premium price compared to the Suzuki DF60. There are probably to reasons for the higher price:
  • a 70-HP engine will cost more than a 60-HP engine, and
  • Yamaha has a reputation as a premium engine choice.

Braco wrote:Am I correct in thinking that a high-thrust 60-HP would provide [acceleration onto plane at full throttle from a standing start] and low-speed to mid-speed cruising that would be comparable to the Yamaha F70, but with ultimate full-throttle boat speed lower?
Top boat speed is always going to be a function of power and weight. An engine with 70-HP should push a boat to higher speed than a 60-HP engine, as long as the weight of the two engines is identical. If the 70-HP engine is heavier than the 60-HP engine, then the improvement in boat speed will be reduced.

There is no basis to predict if the speed of a 60-HP and a 70-HP to accelerate a boat from a standing start onto hydroplane will be the same. This will depend on the power curve of each engine and its weight. There is no method to predict the outcome on a casual analysis. To assume the time to reach plane will be the same is just an assumption and not a fact.

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Phil T
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Re: 1974 CURRITUCK 16 Re-power

Postby Phil T » Sun Aug 21, 2022 11:50 am

I think a 16-foot hull with an 60-HP engine will be underpowered. It's not about brand--it's about horsepower.

A 16-foot hull with a 60-HP [will] not be as attractive or fetch the price of a 70-HP engine at the time of resale, if and when the day comes. Eighty-percent of 16-foot models have a 70-HP engine or higher.

The price delta between the Suzuki DF60 and the Yamaha F70 is not large.

Go with the F70 and rest comfortably.
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