Whaler Central - Boston Whaler Boat Information and Photos

Posted by tom blinstrub on 02/04/10 - 3:33 AM

A 15' whaler with a 70 yamaha 2 stroke will easily go the 44 mph the factory claims. That 90 evinrude will mean an extra 70+pounds hanging off the transom. I would have your kill switch connected to you while piloting that rocketship.I wish you would reconsider a smaller and lighter engine. Good luck and keep it under 50. Tom from mass.

Posted by CES on 02/04/10 - 4:38 AM

You should be fine. There's a guy on Whaler Central from South Carolina that has a Yamaha 130hp hanging off the back of his.

There will be a few folks responding to this thread telling you that you're crazy for putting a larger motor on your boat than what it's rated for. I say just check to make sure you're able to insure your boat with that large of a motor on it by givng your insurance company a call.

Edited by CES on 02/04/10 - 4:39 AM

Posted by tom blinstrub on 02/04/10 - 5:10 AM

Hi rusty hook, I owned a 1976 15' whaler years ago and I swear my capacity plate said 75 hp maximum. Around that time johnson made the three cylnder 75 hp stinger motor which had a nice orange paint job. Later on I believe whaler changed the rating to 70 hp. You could settle an argument Im having with a friend about this. Does your boat have the capacity plate still? Thanks Tom from mass.

Posted by theo on 02/04/10 - 8:27 AM

I have a 90 Nissan in my shop waiting to go on my 15 as soon as I get the tilt/trim repaired. I'm insured with Farmers. They told me 20 hp over the rating was not a problem for them.

It's going to be pretty fast and somewhat of a handful in the corners, but I can't wait. A 60 hp on that boat is too tame for me.

It's a personal choice and the responsibility for any consequences equally personal.

Posted by George More on 02/04/10 - 2:27 PM

I have built 6 15' whalers with ranging with 35-70hp motors. The 70hp Yamaha boats I have built will easily push the boat around 42-46 mph depending on a whether you use a 16 or 18 Yamaha prop. This carries the boat very well, can tow a skier, and is overall a good way to set it up. I have yet to place a 90 hp model on one, as typically insurance companies don't look to favorably on motors over factory HP limits. Sometimes they wont even insure them. Typically when a boat company places limitations of HP, there is a good reason.

I have seen several guys out there with 90hp with not much more speed gain that the 70. However, they are using props that are too little in the pitch and most likely high in the diameter. I would think that the 90 is fully capable of 50 mph when setup properly.

With the 70, it carries the boat really well. it has tremendous acceleration for any boat, and the boat when trimmed and at 5500 rpm is on the verge of chine walking. Chine walking is a point at which the boat starts rocking back and forth violently and it can be VERY dangerous.

Believe me I love HP and speed more than most anybody, and the 70 HP Yamaha 2 stroke is a lot of motor for a 15 and gives an excellent power to weight ratio. I have seen some with 60hp Yamaha 4strokes, but the boats sit lower in the water and cant hang when it comes to top end. If you are looking for a speed demon, then put on a 70, pull down the diameter on the prop and push up the pitch. The boat will be a little slower out of the hole, but will be quite fast.

Posted by dauntless-n-miami on 02/04/10 - 5:45 PM

#10

Hey there Rusty Hook, I own a '96 Dauntless 15 which the previous owner had repowered with an '07 Yamaha 90 2-stroke. the 70-75 hp it had was ok he claimed but, with 4 adults, fishing gear and a cooler with enough consumables the Dauntless would struggle to keep pace through a 2 foot chop. I enjoy and respect the power and piece of mind the Yamaha 90 affords me when the chop kicks up a bit or a reckless boater decides to make a hasty course change into my heading. The previous owner had the boat insured without issue regarding the h.p. increase with Progressive. I did some shopping around for boat insurance and the engine size was not an issue but, I live in So. Fla. Things might be different else where regarding displacement increase. A similiar thread was discussed some time back and a few W/C members posted a formula to calculate maximum h.p. versus hull length if my memory serves me correct. Post a thread asking for details on that formula, I'm sure a member or two will chime in with the info. Good luck and happy boating.

Posted by rusty hook on 02/04/10 - 8:57 PM

#11

The reason I am putting a 90 hp on this boat, I have looked for about 2 months for a good used or rebuilt 60 or 70hp to go on my boat. There are none to be found down here near Houston, except junk or so over priced I can not afford it. I KNOW, I HAVE LOOKED!! So a friend of mine suggested a 90 and there are plenty of them around here. All the used motor dealers say, its the economy or gas prices is the reason nobody is getting rid of them. Makes sense to me. I'm not a speed demon, I only run my motors about half to 3/4 open most of the time, except when its bad weather coming in or just blowing the sutt out every once in awhile! Im 69 and and have had about 25 boats "so it aint my first rodeo"! Thanx for the concern and comments. Three boats ago it was 1 17' Skeeter bass boat with a 130 Yamaha that topped out at 65 by GPS

Posted by CES on 02/05/10 - 6:51 AM

#14

RH, we all thought this WAS your first Rodeo! Lol, just kidding.

Yep, I'd say go for it, you have plenty of wisdom when it comes to boating. You had a 130 on a 17'......and ran 65mph on that critter, I'm sure you can handle a 90 on a 15'.

Have fun and post pictures when you get a chance.

Posted by Bake on 02/05/10 - 4:44 PM

#16

my brother in law has a 15 with a 88 spl Jhonson. The same v 4 you have in a 90. I owned a 15 with a 70 Yamaha and the two boats spent a little time side by side at the lake.

First observation was that his boat did sit a little lower in the stern but not to the point of taking on water or anything.

second observation. The two boats ran the same speed at wot. I am sure he could have propped up and got me. Granted he could run circles around me from the hole shot but running down the lake planed out he was surprised to find out the old 70 yamaha was right out beside him.

That being said if you have the motor I would hang it the ole girl and take her for a spin.

Posted by rusty hook on 02/05/10 - 6:49 PM

#17

My 90 hp is dual carbs, not the 4 carbs. I tried for over 2 months to find a 60 or 70 Johnson, Evinrude or Yamie, but none around. Now I got my 90, there will be a hundred of them boogers show up!!! I have also added a fiberglass center console and a flip-flop seat w/cooler underneath and brand new steering and shift controls and kill switch. The wood was all butchered so that is why I went this route.

Posted by Marty Johns Isd SC on 02/06/10 - 1:23 PM

#18

Hey Rusty Hook, I have a 2001 90 hp two stroke Johnson on my 1991 15' Whaler. I bought it that way knowing that it was 20 hp more than the max rating of 70 hp. My boat does fine with it even though a 60 or 70 hp two stroke would be much more efficiant on the gas. The transome has been fine so far and the hull seems to sit about an inch lower in the water than other 15' whalers with a smaller motor. Yes, it will fly (close to 50 mph), but I rarely go that fast. My truck says it will go 140mph,but I never go that fast in it. but anyways if the motor ever goes bad or I am in a situation where I would have to replace it I would go with a 60 to 70 new two stroke. No I don't think a 90 hp motor will be a bad thing as long as you don't get speed crazy. Just be careful if you get the boat. Good Luck.
Marty Durham
Johns Island,SC