15 DAUNTLESS Re-power

Optimizing the performance of Boston Whaler boats
asonofsam
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15 DAUNTLESS Re-power

Postby asonofsam » Tue Oct 02, 2018 8:48 pm

I currently have a 1996 Dauntless 15 with a Johnson 70 Johnson. I would like to re-power with a new Evinrude E-TEC 90-HP but, the E-TEC engine weight is a bit more than the existing 70 engine weight. The E-TEC 90 is 320-lbs; the old Johnson 70 is 250-lbs--I guess.What are your thoughts [about the additional engine weight]?

An alternative would be a two-stroke-power-cycle classic Yamaha 90, but new engines of that type are no longer sold in the USA. And I've had my fill of Yamaha corrosion problems.

I have been doing a lot of reading about re-powering.

jimh
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Re: 15 DAUNTLESS Re-power

Postby jimh » Wed Oct 03, 2018 12:01 am

Here is a link to search results for the arguments "DAUNTLESS 15 REPOWER" that finds about 200 articles in the website archives, which should give you plenty to read:

Link to SEARCH RESULTS

jimh
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Re: 15 DAUNTLESS Re-power

Postby jimh » Wed Oct 03, 2018 12:03 am

Before you worry about weight, you should check the capacity plate for the maximum horsepower. The DAUNTLESS 15 hull made c.1993 to c.1997 was rated for a maximum of 75-HP. Cf.: http://continuouswave.com/whaler/reference/specifications.html

The weight of a classic OMC 70-HP will depend on its displacement and the type of trim and tilt.

From a comprehensive listing of the weights of older outboard engines:

3 cylinder 849/920 cc platform, 50/60/70 HP

20 inch shaft, elec. start, man. tilt -- 237 lbs
20 inch shaft, elec. start, trim/tilt -- 250 lbs

(This motor used to displace ~849 cc and was about 10 lbs lighter)


For many years in the recent past, an E-TEC was typically the lightest engine weight at a particular horsepower, but more recently a lot of effort has been made by engine manufacturers to make four-stroke-power-cycle outboard engines lighter. You should look at comparable weights with a four-stroke engine, too.

I do have great admiration for the design of the Evinrude E-TEC 90, 75, and 60 H.O. engines. They have very compact size, and the layout of the engine and its components under the cowling is just beautiful.

asonofsam
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Re: 15 DAUNTLESS Re-power

Postby asonofsam » Wed Oct 03, 2018 6:57 pm

Thanks for the search links, I have read a lot of them. You are correct, the [manufacturer's required capacity] plate says 75-HP.

The E-TEC 75 [and] E-TEC 90 weigh the same and are very close in cost. The question really is the weight. I could put on an E-TEC 75 and not exceed the rated horsepower, but the weight is still the question.

The four stroke Yamaha F70 is comparable in weight to the old OMC 70. I've been through the dry exhaust corrosion problem and other corrosion problems with my Yamaha F225 on my other boat, and I would really like to try something different.

Evinrude offers a 7 year warranty, no one else close to that. Thanks again. I'll keep reading.

jimh
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Re: 15 DAUNTLESS Re-power

Postby jimh » Thu Oct 04, 2018 9:02 am

I didn't realize the Yamaha F70LA weighs 257-lbs. The E-TEC 75 or 90 weighs 320-lbs. That is quite a difference: 63-lbs. But a starting battery weighs about that much, so if you move the battery out of the stern for the E-TEC rigging you could reduce the effect of the engine weight gain.

Another consideration is the the engine displacement. The F70LA is only a 996-cc engine; the E-TEC is a 1,295-cc engine. That's about 300-cc or 30-percent more displacement for the E-TEC. And the horsepower favors the E-TEC. The E-TEC 90 would be a much stronger engine. I think the E-TEC 75 would be much stronger, too, as it probably produces more than its rated 75-HP.

The offer of a seven-year extended warranty is certainly an attraction for me, too.

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Phil T
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Re: 15 DAUNTLESS Re-power

Postby Phil T » Thu Oct 04, 2018 11:05 am

Over the years I recall many conversations concerning weight sensitivity in certain Dauntless hulls. I would use the archived search engine to do some searches to verify or dispel this concern.
Member since 2003
1992 Outrage 17, 1992 Evinrude 115

jimh
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Re: 15 DAUNTLESS Re-power

Postby jimh » Tue Oct 09, 2018 7:11 pm

Here is a comparison of the E-TEC 90 and F70LA:

Horsepower: The E-TEC has 28.6-percent more power than the Yamaha (90 v. 70-HP)
Displacement: The E-TEC has 30-percent more displacement than the Yamaha (1295 v. 996-cc)
Weight: The E-TEC has 24-percent more weight than the Yamaha (320 v. 257-lbs)
Warranty: The E-TEC has 133-percent longer warranty (7 v. 3-years)

When you consider these relationships, you can't really throw out the E-TEC on the basis of its higher weight. The weight increase with the E-TEC is the least percentage increase in the four relationships. For that 24-percent more weight you get 28.6-percent more power, 30-percent more displacement, and 133-percent longer warranty compared to the lighter Yamaha. If you really have to get the lighter engine, they you will have to accept less power, less displacement, and less warranty.

asonofsam
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Re: 15 DAUNTLESS Re-power

Postby asonofsam » Tue Oct 09, 2018 9:22 pm

I agree: the E-TEC has it all over the F70--except weight. I spoke to Nauset Marine on the Cape, a Boston Whaler dealer, as well as Yamaha, Mercury, an d Evinrude dealer. They advised the 320-lbs E-TEC was too big for [a 15 DAUNTLESS]. And I kinda proved it myself by placing a couple 5-gallon buckets of water in the stern to simulate the extra weight. One gallon of water is about 8-lbs. Scuppers flanges were tangent with the waterline, resting attitude of the boat was greatly affected. With just myself in the seat scuppers were in water. That's with a 12-gallon tank under the seat, and the battery in the console. I could always load people forward, but as much as I'd want to stick on a 75 or 90 E-TEC, I think it compromises the stability of the boat.

After discussions around I've narrowed it to three conclusions.
  1. Rebuild power head on the three-cylinder Johnson loop-charged engine, considered one of the hardiest outboards ever built. Easy to work on, lots of parts available, cheap.
  2. Look for a Yamaha 90-HP two-cycle three-cylinder, either low hours or rebuilt powerhead
  3. The F70 four-cycle. Fuel injection, new electronics, brand new. Warranty.

Nothing else is really available in the 70 to 90-HP range.

Thanks for keeping this in mind. I'll see if I can post a picture of the scuppers with the 70 plus a second picture of them with the additional weight.

OldKenT
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Re: 15 DAUNTLESS Re-power

Postby OldKenT » Wed Oct 10, 2018 6:46 am

From October 1 to November 19, 2018 Yamaha is now offering six years of warranty: three years of its base warranty plus three years of its Extended Warranty, plus a $400 rebate on the F70LA.

Jefecinco
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Re: 15 DAUNTLESS Re-power

Postby Jefecinco » Wed Oct 10, 2018 10:32 am

Some engine manufacturers only provide third party policies after the expiration of the basic three year warranty. Generally third party policies are less desirable than manufacturers warranties.
Butch

jimh
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Re: 15 DAUNTLESS Re-power

Postby jimh » Wed Oct 10, 2018 3:52 pm

asonofsam wrote:...proved [that an E-TEC was too heavy] by placing a couple 5-gallon buckets of water in the stern to simulate the extra weight. One gallon of water is about 8-lbs.


Two 5-gallon buckets would be 10-gallons of water. Freshwater weighs 8.33-lbs per gallon, so two 5-gallons buckets will be 83.3-lbs, ignoring the weight of the two buckets.

The E-TEC is 63-lbs heavier, so the test conditions were 20-lbs heavier than the E-TEC would have been. The position of the weight affects how it influences the boat trim. Since the E-TEC weight hangs off the transom, and the two buckets were probably still in the boat, the test with 83.3-lbs in the stern was probably a good test to simulate 63-lbs greater engine weight hanging off the transom

flymo
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Re: 15 DAUNTLESS Re-power

Postby flymo » Sun Oct 14, 2018 7:16 am

The decision comes down to cost and what characteristics you're looking for.

The classic two strokes are going to be much noisier than the F70 which may matter if you value cruising around quietly. The two 70s will perform about the same, when set up properly, but of course the 90 will have a lot more get up and go. The F70 will be more fuel-efficient, particularly at trolling and cruise speeds; that may not make a lot of difference to your wallet, but it will extend your endurance / range. And of course a new F70 will be much more expensive than either buying a used 90 or rebuilding your 70.