1964 Sakonnet Re-power with F70

Optimizing the performance of Boston Whaler boats
SeaClassic16
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1964 Sakonnet Re-power with F70

Postby SeaClassic16 » Fri Mar 05, 2021 2:01 pm

I have a 1964 Sakonnet 16 that I plan to re-power in Spring 2021. I decided on a Yamaha F70 to keep the weight in line with the 1989 Mercury 90 that we are removing.

Q1: What is the best propeller?

Q2: Why are people running a jack plate?

Q3: What should I watch for?

I will appreciate any replies.

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Phil T
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Re: 1964 Sakonnet Re-power with F70

Postby Phil T » Fri Mar 05, 2021 4:26 pm

The F70 is the lightest in its class and is a very good candidate for the classic 16/17 models.

A jackplate only assists if one transits "skinny" water on a frequent basis. The added weight does not improve wide-open-throttle (WOT) by much. Unless there is a truly compelling reason, skip it. If the dealer recommends it due to engine mounting, see below.

Many owners installed an F70 on a 16' hull. They did extensive prop testing over the years. Their recommendations include:

13.25x14 PowerTech SCP
13.25x14 Yamaha Performance Series
13.25x14 Turbo 1
13x17 Yamaha Painted Stainless Steel

**Note: Size only applies to the make/model listed and is not transferable.

With one of the recommended props the engine should be rigged "3 holes up", expect a WOT of ~35mph @ 6100 rpms. This mounting recommendation may require the dealer to plug/redrill the lower holes. In the olden days dealers were conservative and mounted the engine sitting on the transom and the lower bolts were drilled for the blind holes. The dealer should fill the lower holes with plugs coated in epoxy and should not use dowels. A template of proper engine hole spacing is available. A jackplate is not recommended as it is a bandaid to avoid the transom work.

Do not skimp and install an aluminum prop. It will not protect your gearcase (old mechanics tale) and would be the same as purchasing an $80,000 pickup and then installing big wheel front tires.

Repower demand is high so try not to wait long before buying the engine. Many installers are already fully booked for the spring and inventory is tight.
1992 Outrage 17
2019 E-TEC 90
2018 LoadRite 18280096VT
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jimh
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Re: 1964 Sakonnet Re-power with F70

Postby jimh » Sun Mar 07, 2021 8:11 am

When buying a new engine, ask the selling dealer to quote the inclusion of a Yamaha steel propeller and on-water testing to confirm proper operation as a line item. Yamaha propellers generally give good performance.

If there were only one propeller that was always “the best” propeller and this were widely known, then the manufacturers of other propellers would eventually be forced out of business or would have to make identical copies of “the best” propeller and sell them at lower prices. Since this does not seem to be happening, one could infer there is no one single propeller that is “the best” propeller and there are many “good” propellers.

By testing many good propellers you may discover some marginal advantage to one, either in a slight improvement in some element of the broad definition of “performance” or in an advantage in lower price for equal performance or even slightly reduced performance.

For example, after testing perhaps ten propellers, my data showed one propeller had a very slight improvement in fuel economy compared to another. The “better” propeller cost $600. The other propeller cost $100. (Those prices were the costs available to me at the time.) I decided that the very slight improvement provided by the $600 propeller was not worth the $500 increase in its acquisition cost. The other propeller was “the best” for me.

In general a three-bladed steel propeller without a high blade rake angle and with progressive pitch across the blade face and with cupped blades and with a propeller load curve that is a good match for the engine power curve will deliver very suitable performance, which includes rapid acceleration, good top boat speed, and good fuel economy.

SeaClassic16
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Re: 1964 Sakonnet Re-power with F70

Postby SeaClassic16 » Tue Mar 09, 2021 2:14 pm

Thanks for the advice guys. I've already got a dealership lined up for me, it will just take a couple months for the [Yamaha F70 engine] to come in. I can play two-stroke-mechanic for another couple months. No need for a jack plate since I'm in Seattle and in the saltwater there is plenty of depth out here.

Give a specific links to these plugs.

I'll read through some other posts and pick a propeller. I feel like people have gone through this enough for me to be able to choose one.

SeaClassic16
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Re: 1964 Sakonnet Re-power with F70

Postby SeaClassic16 » Thu Apr 29, 2021 5:46 pm

Hey Jim and Phil. Thanks for the detailed replies.

The [Yamaha F70] engine was ordered several months ago. and it should arrive in May. I'm buying the [Yamaha F70] engine along with some friends. We are trying to keep down the installation costs.We're pulling the old engine and running the rigging back to the stern so all is ready for [the dealer to mount the new engine on the transom]. I am having the dealership just mount the engine onto the transom.

Without having to do a day of testing with it, what propeller should be used [with the Yamaha F70 on the 1964 SAKONNET]?

I know that [actually testing a propeller on the boat and the engine on the water] would be ideal, but I'd rather avoid [the on-water testing].

Most often [the 1964 SAKONNET boat with the Yamaha F70] will be run with a few guys in the boat and either fishing gear or crab pots on Puget Sound. There are two 12-gallon fuel tanks under the console.

The battery is still in the stern port quarter against the splash well.This summer I will probably sort out moving the battery forward but that space is currently takien up by the fuel tanks.

Again thanks for the advice on prop selection.

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Phil T
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Re: 1964 Sakonnet Re-power with F70

Postby Phil T » Fri Apr 30, 2021 8:30 am

This list

13.25x14 PowerTech SCP
13.25x14 Yamaha Performance Series
13.25x14 Turbo 1
13x17 Yamaha Painted Stainless Steel

which was included in the second post came from 16-17 owners who installed an F70 and tested multiple propellers.

These are the recommended propellers from that testing.
1992 Outrage 17
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jimh
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Re: 1964 Sakonnet Re-power with F70

Postby jimh » Fri Apr 30, 2021 9:11 am

SeaClassic16 wrote:Give a specific link to these plugs.

I believe that the use of "plugs" as mentioned above is in reference to filling old engine mounting holes. The "plugs" are something you would make yourself with a plug cutter and marine plywood. I don't know where you would buy them ready-made. Perhaps a woodworking store might have some.

Plugs are cut by a plug cutter. If you are only going to cut a few plugs in your lifetime, buy an inexpensive plug cutter set, less than $5 at junky tool stores.

The plywood should be marine plywood or at least outdoor plywood so the glue is not water soluble. You just need a scrap piece to cut the plugs. Go to a lumber yard and see if they have a scrap piece in their waste bin. Or you could cut a plug from a board of an appropriate wood, perhaps mahogany.

SeaClassic16
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Re: 1964 Sakonnet Re-power with F70

Postby SeaClassic16 » Fri Apr 30, 2021 4:07 pm

Phil T--thanks for the list. I do a bit more research and pick [a new propeller].

jimh --gotcha; I have a chunk of ipe that I've used for other boat projects. I'll make my plug{s} out of that.

I'll let you guys know how [the 1964 SAKONNET 16 is] running once I get the [Yamaha F70 engine rigged].

Thanks!

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Re: 1964 Sakonnet Re-power with F70

Postby jimh » Fri Apr 30, 2021 11:36 pm

SeaClassic16 wrote:I have a chunk of ipe that I've used for other boat projects. I'll make my plug{s} out of that.

The wood for the plug should be similar to the wood in the transom. I am not familiar with ipe wood. If it is a hard wood or a very dense wood, it probably is not the best wood for the making a plug to blend with marine plywood.

SeaClassic16
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Re: 1964 Sakonnet Re-power with F70

Postby SeaClassic16 » Thu Jul 08, 2021 12:07 pm

Thanks for the help on this everyone.

I just heard on July 7, 2021, that the new F70 engine arrived to the dealer in Edmonds, WA. I placed the order on March 9, 2021, and I was initially given a delivery date of May—in case anyone is wondering what supply chain delays are looking like.

Duckmanreno
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Re: 1964 Sakonnet Re-power with F70

Postby Duckmanreno » Fri Jul 09, 2021 12:09 pm

That is good news. Please keep us updated
1974 Montuak
2021 Yamaha F70

SeaClassic16
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Re: 1964 Sakonnet Re-power with F70

Postby SeaClassic16 » Thu Jul 15, 2021 12:47 pm

The new Yamaha F70 engine is getting installed. Ineed to clarify for the dealership exactly which holes to use on the Yamaha F70.

I've read a post and looked at the Whaler bulletin.

But I need more of use these holes and not these vs the run down on all possible options.

I'm mounting the engine three-holes-up. The dealer said he had to fill a hole and talked about using a lag bolt for the lower [engine mounting bolts].

I don't think this is what has been best practice.

At the link below find a couple images what is going on from the last engine and whatever was going before.

https://photos.app.goo.gl/8NkGDPSVg4sPVEKs7

[Give me a] run down on what to tell [the dealer installer] when I get back to the shop.

Thanks.

SeaClassic16
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Re: 1964 Sakonnet Re-power with F70

Postby SeaClassic16 » Thu Jul 15, 2021 1:11 pm

Reading this bulletin

https://continuouswave.com/whaler/refer ... 84-10.html

and reviewing the current holes [in the transom of the boat under discussion, the transom holes appear to be] drilled at an upward angle.

Once I get the F70 hanging over the current holes I will know how the engine will line up [with the existing holes in the transom].

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Re: 1964 Sakonnet Re-power with F70

Postby jimh » Thu Jul 15, 2021 9:47 pm

For advice on mounting engines on boats with shallow engine splash wells, read the article on that topic at the top of this forum:

https://continuouswave.com/forum/viewto ... f=7&t=5808

Also read the FAQ on engine mounting at

https://continuouswave.com/whaler/reference/FAQ/#Q8