Glen-L.com

I built the Tahoe 19 @ 20'-6". I wanted pretty much traditional performance.

'50's engines were about 160hp, 6 cylinders with about a 3300-3400rpm redline. They ran a 1:1 Velvet Drive with a 12x12 pitch prop. The engines came in at about 1000#.

I planned to use the boat along the Alabama Gulf Coast and diesel just seemed safer. The Yanmar 160hp has very similar specs. But, I the best match i could find is the ZF-45a 1.23:1 reduction gear with a 13x16 pitch prop. All the ratios are about hte same including engine max torque.

The dealer asked if I had considered the 125hp, turbo 4 cylinder that turns 3900rpm and weighs 300#'s less. The weight/hp ratio is about the same and the fuel comsumption is less. The engine sound of the higher reving 4 is about the same as the 6 would be.

WOT is 39mph. That's about the same as design.

I'm happy with my choice. But, I rarely go out in Mobile Bay and I don't get the hours of use that I'd like. I modern 4 cylinder gas engine would be a lot cheaper choice.

Bill

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Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
Tahoe 19 Build

When I built my Sea Knight, i knew i wanted enough power to get it up on plane with a full load. When my grandfather had built the same boat in the 60's he powered it with a v-4 Evinrude 75 hp. He had said that with full gas tanks and a full load the boat had trouble getting up on plane. The same boat was repowered with a 115 Evinrude in 1974 and that seemed to be more then enough power.

When i built mine I started out with a 1996 Evinrude 115 which seemed to do the job quite well...untill the motor died. When my wife and i decided to make the investment in a brand new motor I considered many things. I wanted fuel economy and I wanted to keep the weight of the motor itself down. The weight concern ruled out most new four-strokes. That led me to 2 stroke Direct Fuel-Injected power. There are several options on the market out there. Tohatsu has a DFI motor now, but they are very new and I don't know enough about them, further more i don't know much about getting them serviced.

The Evinrude E-tec was my best option for several reasons: 1. THere are a lot of Evinrude Mechanics out there 2. I found a good deal on a brand new (still in the crate) one. 3. I come from a long line of Evinrude owners (all the way back in to the 50's) and Evinrudes are all i have ever owned 4. I know people that have them and I read a lot of consumer reports that give them very favorable reviews.

When i Repowered with the new Evinrude, i didnt go for 115 hp. I went with 90 (it was the same weight as the 115 i was replacing). THe 90 was more then the 75 (that my grandfather told me may be underpowered with a full load) and was about 40 pounds lighter then a new 115.

I am very satisfied with the performance. I may need a different prop, but even with what I think is the wrong pitch on the prop the boat is able to get 6 full grown adults, 30 gallons of fuel and one baby up on plane to run at 25 MPH. Most of the time i am only run with around 15 gallons, me and my wife and the baby at around 30 mph (i really just want the extra power for the fewer times I will need it). And the fuel economy is amazing.

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Built the 17' Glen-L "Sea Knight"

I have been boating for almost 30 years with a boat that has a 115hp I/O. I drank water for far too long for far too many years getting up on slalom. I was determined to make sure Midnight had the power to yank my arms off.

I checked out a lot of ski styled boats and found the 5.7L a common choice. I then had to deal with the low deck on the Riviera with only about 27" clearance between the keel and deck frames. Research found the PCM Excalibur 5.7L using the 1.23:1 downangle tranny would fit without any deck modifications. Fit it did with only 1/2" clearance.

However, the 343HP is far more than the boat needs. But I don't drink water anymore being dragged behind an underpowered boat. So I am most happy.

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Dave

My Riviera build - the Midnight Cry Project

Video of Midnight in Action
Blog

Few things in the world measure up to the thrill and satisfaction of boating in a boat that you built.

I knew from the beginning that I was going with a straight inboard, the only question was which one. Since the double Eagle was the first boat I built of this size, I was going the cheapest route merely to prove my workmanship in the process. I decided if the hull ran well, then I would upgrade to a more money engine. Cummins 4cylinder diesel was my ultimate goal. a work buddy offered me his old 'glass boat with a 3.0L I/O for cheap money, I snatched it up. I sold off all the I/O parts/trailer and whatever else and that yielded money to put rings & bearings in the little motor, plus the straight inboard conversion. I knew that little motor was smallish so I went with a deep ratio gearing (I wanted a slow prop for top water trolling anyway). It all worked out well, and the price of diesel fuel skyrocketed in the process, so the original Cummins diesel target is now in flux. I often wonder why I haven't upgraded the engine before now, but it seems to fill the bill nicely as is.

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God Bless our Troops; especially our Snipers

I read and followed Dave Lott's blog and postings carefully and decided on the 305 cu. in. version of the SBC engine at 275 hp. I am still shaking down the finished boat but 40 mph (GPS) at 4000 rpm with WOT calling for 5000 rpm suggests that top speed will be close to 50 mph with 13 x 13 prop. As Dave has written, the hull design is for about 40 mph and over-driving it is at your peril. I haven't enough high speed experience yet to know whether porpoising will be a problem.

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Bill

Built a Monaco named: Princess

And she rides like a dream at that speed as well doesn't she?

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Dave

My Riviera build - the Midnight Cry Project

Video of Midnight in Action
Blog

Few things in the world measure up to the thrill and satisfaction of boating in a boat that you built.

At 40 mph in smooth water she rides smoothly without porpoising. Not too much of a thump riding over a wake. Stay tuned for higher speed reports. From the first everything functioned as expected. She is absolutely dry inside. Nary a drop through the "dripless" shaft seal.

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Bill

Built a Monaco named: Princess

Typically, in the past it was the highest HP rating I could find, that I could shoe-horn into a hull.

Now: anything that isn't made by Gov't Motors.

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Some plan to stroll through Saint Peter's Gates, I plan to go through them at 150mph... backwards... in a screaming ball of flame, with a glimmer belt wrapped around my head, and a NOx button in my hand.

I took somewhat unusual (backward)approach by identifying criteria in the boat I wanted to build first:
had to be displacement hull, diesel, economical (fuel is $6.50 a gallon here), reliable and approx. 20' length with intended use of 70% fishing 30% cruising..
Based on that I shopped for engine that would do the job and came across a deal on 20 HP Volvo diesel MD2020 New old stock (patience pays big here)...
Once engine and drive train (most expensive components) were obtained, I selected Bo Jest as perfect fit for my needs and engine capabilities and went from there... I find that to be the most economical approach, get the most expensive components out of the way then select the boat that fits the performance and needs criteria.
Ciao,
Sam

Hi gents,

Sorry to hijack this post but reading all your messages and type of engines described. Aren't you worry about the weight of these big engines? I'm new to it but going to different plans, the maximum of I/O with drive is around 700lbs (the lighter is mercruiser 3.0 and weight more) and for inboard v-drive 800 to 900lbs? For sure your big engines weight far more or I'm totally wrong or you redesign the hull!

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Happy sailing

JB
Belphil
UK - Philippines

Actually no, we dont worry about weight of straight inboard, since they are often times lighter than a comparable I/O.
An I/O is quite heavy considering all the exotic cast aluminum involved. The I/O engine by itself is same as a bobtail inboard, then add the transon mount, gimbal, medsection, lower unit, plus the trim cylinders, trim pump, power steering, it all adds up.
A small block I/O weights about 900lbs, perhaps 1000.

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God Bless our Troops; especially our Snipers

Correct I/O is heavier maybe with exception of the lighter Mercruiser.
Got it now but what about inboard with V-drive? Just try to figure out how big engine I could have on mine and how much space I will need to have in cockpit!

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Happy sailing

JB
Belphil
UK - Philippines

Just to add my 2 cents to the mix here.

I picked my Malahini outboard motor based on 2 basic factors:

- Big enough to pull someone as big as me on water ski's with 3 still in the boat and a full tank of gas. My complete rookie guess was that I needed a 50 HP or larger engine. There are plenty of 50 HP motors for sale around here as a lot of 'basic' fiberglass production boats are sold with them, and the owners eventually find them underpowered on their heavy fiberglass hulls and they end up upgrading to a bigger motor.

- New'ish. I am not a mechanic and while I am not totally useless with a wrench, I am not about to restore and maintain a classic. There are plenty of 'deal' motors in my nick of the woods that are older than me and god knows how much money I could blow getting one fixed.

I shopped around a lot, because the engine was my single biggest expense and the market where I live has a lot of wealthy folks willing to drop big $$$ so finding good value was a bit tricky. I did a bit of buy & sell on some older stuff, and found a nice 1989 90 HP Mariner (Merc by another name) that I had compression tested and seemed in good shape.

The biggest issue I had was the orange & red pinstripe letters on a metallic dark gray header. Not pretty in my eyes. I sanded down the cover, repainted it a classic white, put on some embossed chrome letters and presto-chango... it looks a bit more classic

I don't know what my prop is... fastest GPS speed I hit was 40.1 mph @ 5,500 rpm on a half tank with just me in the boat. Its closer to 35 mph with a full crew. I can pull a tube with 2 kids on it no problem, and with the extra 5 degree's I built into the transom angle I can trim-out any nose hopping (porposing) and she runs smooth (as the waves will allow).

The only down side is the engine weight. By transom sits another 4" low from the design water line. If it was possible to get 75 HP at a lot lower weight I'd seriously look at it.

But otherwise I am very happy with the way it turned out. I am actually looking for some trolling options right now for fishing.

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Ian (aka Iggy)
My Malahini Build

I just had one lying about doing nothing, I thought that would look good in a classic wooden runabout,so I chose the riviera ;