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Author Topic:   Power for classic 15"hull
Alex K posted 09-03-2004 01:38 PM ET (US)   Profile for Alex K   Send Email to Alex K  
I plan to outfit an Alert 15" hull as a centerconsole in the style of Clark Roberts Killer. Cetacea page 28 I think.
Clark provided me with a lot invaluable knowledge about this hull and his setup, even only one day after his Spruce Creek Navy got whacked by Charly. Great people on a great forum. As the Alert is from commercial departement I have "the freedom of choice";-)Definately!
Powersource should be 4-stroke or a clean DI 2-stroke.
My favourites are Mercury 60 EFI or Evinrude E-TEC 60HP while my heart tends to the Evinrude. I learned from Clark that a large lower unit is a disadvantage for a boat of this size, the E-TEC has the large V-4 lower unit. Haven't heard anything about the performance of this 60HP E-TEC, only about the 75 and 90 3-cylinders. I heard a lot of positive things about the Merc. Any experiances or opinions on these options?
Good luck to Clark and all the other in Florida
4whaler posted 09-03-2004 04:16 PM ET (US)     Profile for 4whaler  Send Email to 4whaler     
Ive had four different 15ft'rs, still have two of them. The lightest motor for the horse power desired is the best. My 4 stroke Yamaha 60 hp is a little too heavy for the boat in my opinion. The 70 hp Yamaha 2 stroke 3 cyl. is almost too heavy for my Mischief. The best motors Ive found are the old 4 cyl. 50 hp Merc. then downrate to 40hp. or the two cyl. 60 hp Evinrude or Johnson. The lighter the better....depends on how fast you want to go....
happypappy posted 09-03-2004 09:34 PM ET (US)     Profile for happypappy  Send Email to happypappy     
I have a 15' with a 1987 3-cyl 49 cu. In. Johnson. The boat takes that weight just fine and runs well with it. Nice thing about the larger engine is that you can put a load in the boat and the engine does not have to work as hard as a smaller engine to push it.
vermilionwhalers posted 09-04-2004 04:34 PM ET (US)     Profile for vermilionwhalers  Send Email to vermilionwhalers     
Alex - I repowered late 2003 with a 2004 EFI Merc 60hp. Wonderful motor. Just sitting with two full tanks in the back water just comes into the bailers. If I have two persons sitting on the bench behind the center console and I _stand_ on the transom, I will fill the bailer. I would now consider moving the battery to the center console (wish I had done that in the repower).

Dealer mounted using a Transom Tuffner. Also had to dig out some foam to attach in the back; he put in an inspection port. I later filled the cavity with shipping peanuts and humidity absorption. 15 pitch prop. Dole-fin. Planes at about 3500, 15 mph. WOT went 35 on low weight, way trimmed out in calm waters (Kids don't try this at home!) Quietest motor in the universe. You would love the Merc.


Doug Johnson

Alex K posted 09-04-2004 07:13 PM ET (US)     Profile for Alex K  Send Email to Alex K     
Thanks for the input so far.
I don't want to go with less than 60HP because I want to ski behind this boat and I'm 210lbs (increasing, could this cause problems!??;-) I'd rather have 70HP, but as I want a 4-stroke or a direct injection 2-stroke, I guess there is no such option. 75HP E-TEC is the same 3-cyl. block as 90HP, weighs 305lbs, sure is too heavy. There is a Tohatsu TLDI 70HP, same problem, 90HP block, too heavy plus they have NO service net in Europe. Thats a problem with Evinrude too, their service net suffered a lot from OMC's bancrupt. And I hear that BRP introduced several software updates for the E-TEC's. So tow the boat and motor maybe 50 miles to get an update on the motor electronics for I don't know how often?
I'm German and I sometimes don't understand the American terms esp. when they`re very specific about boating for example. What do you mean by Transom Tuffner? Is it like a support plate? Why did your dealer remove foam from you`re boat, in other words cut a whole in your Bosten Whaler where there shouldn't be one? The 60HP Merc EFI is not that heavy, about 275lbs, that hull is made for 7OHP and sure will not have any problems with this weight. How much weighed OMC's 70HP from the eightees? Maybe I got something wrong here? What are you're RPM readings at 35MPH?
I want to use a CMC manual Jackplate with 5-1/2" setback.
I plan to put both tank and battery into the Carolina Skiff type console, its a model with a molded in seat in front, is that too much risk?
Is there really nobody to share experience about the 60HP E-TEC?
Freeport Alan posted 09-05-2004 07:21 PM ET (US)     Profile for Freeport Alan    
I had a nice 15' Sport with a 70 carbed Yamaha not too long ago that I had to sell @ the request of my ex wifes lawyers & now have a nice 13' Sport but...
I really believe the 3 cylinder 70 hp engines a great match for that boat, effortless speed, I topped out 48 MPH's , it sat nice in the water..lighter then many 4 stroke engines with less HP..
I believe in most cases in going for the biggest motor A manufacturer recommends because it's less of a load on the engine which adds to engines service life..
Allthough I never owned a 4 stroke outboard & with the great gas milage they get I'd be tempted to try one on this boat if $ wasnt an object only thing is the extra weight "may" be a problem but problably not..
David Jenkins posted 09-05-2004 11:03 PM ET (US)     Profile for David Jenkins  Send Email to David Jenkins     

The problem with 275 pounds on a jackplate with 5 inches of setback is not the strain on the transom. The problem is the 15' will sit too low in the water. It doesn't look right. And if you walk to one side of the boat in the stern, you can take on water over the gunnel. My advice is to forget the jackplate. Otherwise, look at the 203-pound Honda 50. Or get a light-weight 2-stroke 70.

Best of luck.


bc posted 09-06-2004 08:57 AM ET (US)     Profile for bc    
The eighties 70hp weights in around 220. I saw some pictures of a alert and it seems to sit lower in the water than the classic 15 (The pictures are linked to this site). Just Saturday, I down sized to a 2-cyl Omc 50hp from a early 80's omc 70hp that was worn out. I've only had it in the water once. I personally think the 70 is a little big for this boat...I like the profile better with the smaller motor. The boat will handle the 70...but two things 1. Top speed can get a little chine walking 2. The engine drain well will keep water inside. Good luck.
Freeport Alan posted 09-06-2004 09:41 AM ET (US)     Profile for Freeport Alan    
I've got a 1994 40hp 4 cyl. Merc on my 13 Sport now & I have nothing but great things to say about this motor. I believe they make a 50hp 4 cyl. { maybe not 1994 though } that motor would be a nice match fro the 15 ..
Motor weighs 177 lbs, very light..
Alex K posted 09-06-2004 05:56 PM ET (US)     Profile for Alex K  Send Email to Alex K     
Gasoline is about $ 5,20/gallon in Germany right now, and the tendency has only one direction: up. How much is it in the US? I want to ride that boat not only occasionally and I'm not Rockefeller, so that is an important fact to consider. I need an engine that has a good MPG. I agree with all of you who suggest an old style 2-stroke with a lot of power for the weight and a simple technology. Not much electronics, all mechanical, simple to maintain, but the fuel, way.
So anybody has experience with a direct injection 2-stroke that fits to this boat?
vermilionwhalers posted 09-06-2004 05:56 PM ET (US)     Profile for vermilionwhalers  Send Email to vermilionwhalers     
Hi, Alex:

I'm from Minnesota and didn't know what a Transom Tuffner was either until it appeared on my boat! Basically a support plate about 18 inches wide mounted on the inside of the transom. As to the foam removal, it was just a small amount to get access to the lower part of the transom. My dealer told me it was necessary to mount the Merc at its proper depth. Had to remove material to get to and secure the bolts from the inside. I was a bit surprised but it seems to work fine. WOT is 6,000 RPM.

The Merc weighs 248 pounds according to their specs (maybe more with Trim & Tilt?). I looked through the
Whaler reference and could not find a max motor weight listed for my boat (1983), but I'm sure the Merc is within the limits.

Water skiing pulls kids okay and tubers. I wouldn't want to try to pull an adult out of the water on one ski...go for a 70 if you need that.


Doug Johnson

Alex K posted 09-07-2004 05:24 AM ET (US)     Profile for Alex K  Send Email to Alex K     
Hey Doug, look at the time we both posted our last message! Same minute!
I want to use a CMC manual jackplate to solve this problem without modification to the hull. On the CMC homepage you can see that setback plate with 5-1/2" or 4" setback, but I only found the 5-1/2" from different suppliers, Boatersworld, Basspro and Cabelas but not the 4 inch type. 4" would be better for the weight distribution for this hull, anybody knows where to get this?
skred posted 09-07-2004 08:14 AM ET (US)     Profile for skred  Send Email to skred     
My '85 Center Console 15 with Yam 70 (same year) didn't affect the trim of the boat at all. I located the battery and the 6.5-gal. tank under the console, which I hinged at the front for access. Boat went so fast it scared me. Updated/downsized to a 2001 Merc 50 4-stroke. Plenty of power and speed - excellent gas mileage. Stayed away from jack plates, etc, and the boat still ran within 3-5 mph of the old 70 hp.... (40 or so...)
scaleplane posted 09-07-2004 08:47 AM ET (US)     Profile for scaleplane  Send Email to scaleplane     
Alex K

I have a 1976 15' Sport with a 2003 40HP Johnson two-stroke. With two people (about 350 lbs) and a toy poodle on board and 12 gallons of fuel under the rear thwart, it hits a little over 30 MPH by GPS and has a fast hole shot. This is a two-cylinder engine and I get great gas mileage. The 50HP Johnson is close to the same size and weight - would probably be just fine for skiing.

15ftlover posted 09-09-2004 09:48 AM ET (US)     Profile for 15ftlover  Send Email to 15ftlover     
I have a 1978 15ft striper model and have had three power plants over the years;
1978 mercury 70hp 2smoke carb-WOT 50 mph with SS prop, skiing no problem, pretty thirsty but not an option any more (excellent skiing motor)
1991 mercury 40hp (also available in 50hp) 4cylinder 2smoke carb-WOT 33 mph, good fuel consumption, lighweight (185 lbs) but not powerful enough to carry more than two in boat while skiing a 3rd, sluggish to plane with 4 adults, but great static trim and the most comfortable riding motor in a chop due to less stern weight and lower bow angle of attack (an excellent fishing motor)
2004 mercury 60hp EFI smallfoot-WOT 42.7mph at 6000RPM with ss 15" heavily cupped prop, 236 lbs so weight is OK but needs a little weight forward to have best 'ride' in chop. Motor will pull me up on slalom (170lbs) and can ski with 4 people in boat. Mileage is excellent (>7-8mpg) especially when skiing because you can keep RPM's around 4200. (probably best all around motor)
I think the smallfoot EFI would be plenty of power and is about 20lbs lighter than the bigfoot version. Your alert is going to sit a little lower than my boat but my current engine can trim all the way clear of the water and my splashwell is dry even with 12 gallons fuel in stern. You could relocate the tank under the forward thwart seat for a perfect setup. I don't see a need for jackplate because of added stern weight.
Good luck in your choices, keep us posted on what you decide
Alex K posted 09-09-2004 10:45 AM ET (US)     Profile for Alex K  Send Email to Alex K     
Hen, I will put tank and battery in a custom center console, so this will take some weight from the transom. Did you have to change anything at the transom to mount the 60 EFI? What prop exactly are you using and which standard alu prop would do the job best in your opinion? As I can get no infos about the E-TEC and the 60HP is not even available in Europe I very likely will go with the Merc. Can you send some pics?
15ftlover posted 09-09-2004 05:20 PM ET (US)     Profile for 15ftlover  Send Email to 15ftlover     
I am using a older quicksilver (I believe) that was the original prop on my 70hp merc. We had it cut down at a prop shop but it is a 14inch pitch and 10inch diameter with a little cupping added by the shop (behaves more like a 15inch although stamped 14). We tried an aluminum 10 x 17inch pitch and it would not get into the upper operating range (gave us about 5400 RPM and only 36mph) We are right at 6000RPM WOT now but would think a 15 inch or 16 inch stainless would be the way to go (Sal DiMercurio had some good input on an older post). I am sending you some pics with old prop
high sierra posted 09-09-2004 11:21 PM ET (US)     Profile for high sierra  Send Email to high sierra     
Henry , we've talked before. Just got my new 05 Yamaha 60 FI. Haven't been able to run it yet as dealer gave me wrong prop and then no wiring harness. Got both of them and found needed adapter harness for tach. Prop not sorted out yet. Would like to see what you have done to yours. Pictures? Thanks
Alex K posted 09-10-2004 08:30 AM ET (US)     Profile for Alex K  Send Email to Alex K     
Hen, beautiful pictures, I use one for my desktop now:-)
What bimini top is that and what height is it? Do you think there is a Bimini for a 15" that is high enough to stand at the console, I'm 6"5'!?
15ftlover posted 09-10-2004 09:24 AM ET (US)     Profile for 15ftlover  Send Email to 15ftlover     
High Sierra,
Must be excited about the new '05! Our dealer also set ours up with wrong prop initially-I'll send pics. Alex, the bimini is a three bow aluminum framed one that I think we ordered from Boaters world catalog or maybe West Marine? (It's been about 13 years). I measured the width at the gunnel and then ordered the 48 inch slide tracks to adjust fore/aft positioning. After that I cut the tracks to give me 3ft of travel. Our bimini has been lowered by about 8 inches to make it more stable at speed (cut the longest bow tube where it attaches at the gunnel) I can stand below it but have to stoop just a little (I am 5'8"). Most running I do is seated or with top down. The top easily folds down with two quick snaps. It stores nicely in front of outboard cowel and is out of the way. I think you would have to mount your bimini more forward to allow it to swing down without having to 'slide it up' every time if you wanted to keep it tall enough and be able to fold it easily. Keep us posted on the boat and send pics when ready!

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