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Author Topic:   Best Hull for a Yamaha F70 Tiller

towboater posted 02-25-2011 01:24 PM ET (US)
What classic [Boston] Whaler hull would be best suited for a single [Yamaha] F70, 257-lbs, 20-inch leg, with tiller? I am aware of the Sport model but seems like there is another better suited.
I[']ve given up trying to find time to finish restoring a [1987] Guardian 18 hull and mount twin F70's. How I ended up with a single 2010 low[-hour] F70 sitting [on] a bench is a long story.--Mike

Tohsgib posted 02-25-2011 01:33 PM ET (US)
Your 18 will move Ok with a 70 but a 15/17 would be better. Can you convert to remote or tiller only? In Belize our guide had twin Johnson 65hp commercial pull start tillers. They were connected with a rope so the props would not hit. He would stand between them and steer/throttle with each hand, you don't see that too often in the States.
towboater posted 02-25-2011 02:29 PM ET (US)
Thx Mr Big.
F70 is only 20" shaft.
Im sure the 70 would bring it up on step but thats about it. Im not in a big hurry. Time to kill today, mulling options.

I guess I could trade in the 70 for a 90 for very close to the same cost as selling the 18 and purchase a decent 15/17 hull, blown motor and worn out helm...
mk

littleblue posted 02-26-2011 02:28 PM ET (US)
Best? Gotta be the 15. The motor would work well on a Montauk too. New twin F70's on the 18 would be coolest though. :)
Peter posted 02-26-2011 02:58 PM ET (US)
A 70 HP tiller operated motor on a 15 that has a tendency to chine walk above 39 MPH would be dangerous and probably not recommended by Whaler.
Tohsgib posted 02-28-2011 10:54 AM ET (US)
Considering it says in the brochure that 40hp is max on a tiller 15 and 50 on a 17' I would agree with you but it would be fun and if you set it up correctly it will not porpoise or chine walk. None of my 15's started to walk until about 44 or so.
dgoodhue posted 02-28-2011 12:08 PM ET (US)
Without a Jackplate and having the ablilty to trim the motor out, a 15' with 70hp will not be chinewalking. My 15' does about 41-42mpg before I trim out the motor out. I suspect the jackplate I have add a few mph to my top end as well.
The motor might rip out of your hand on the hole shot or knock you over board if standing.
Tohsgib posted 02-28-2011 03:36 PM ET (US)
Mine as well. She would start walking from about 43ish to 48+ WOT trimmed out shouting a 6' high rooster tail. Still was not bad until you tried to turn. You would bang back the throttle and nail it again to stop the walking...temporarily of course....fun boat.
Tohsgib posted 02-28-2011 03:38 PM ET (US)
Actually there is a guy on here with a 50(20") on a 18 and he says she runs like 28. A 70 I would think would do 32+ but you would need a 8-10" setback jackplate to run that 20" and with a tiller you would be sitting on the transom..literally.
towboater posted 02-28-2011 05:57 PM ET (US)
Thanks.
Yeah, 45 in a open 15 ft boat would be fun.
Ass cheeks on the spash well isnt.
You guys have convinced me I should go back to square one, mount the 70 on the 28 x 12 work float until the Guardian is done, then go with twins and push the work float around with that...or I might even play a little.
One thing I have learned, searching boat sales sites almost daily for a Whaler with worn out engine and helm...there arent any. Im not married to or fanatical about Whalers, but I am convinced, Whaler owners seem to be more concientious about boats and maint than the average bears.
Mike
Binkster posted 03-01-2011 09:04 AM ET (US)
I don`t think any Whaler will give you the adrenaline rush you are seeking. Get something like this. tiller motors are a simple way to have fun.
http://www.youtube.com/watch?v=O_KR4Uv9NM0&NR=1
Tom W Clark posted 03-02-2011 02:31 PM ET (US)
Mike,
I would not put a new F70 tiller on a 15' hull. The combination of a relatively heavy motor combined with a seating position so close to the stern would result in a very stern heavy condition.
The 15' hull is only rated for 40 HP in tiller steering configuration.
The 16'-7" hull would be a better choice. Though it is only rated for 50 HP with tiller steering (the Guardian 17 is rated for 55 HP), I suspect it would be fine.
The Outrage/Guardian 18/19 has a minimum power rating of 75 HP, though a new F70 might be adequate. The more limiting factor here is the 20" shaft length of the motor for a boat that is designed for a 25" shaft length motor.
However, as Nick points out, Bill (number9) has a 20" Yamaha T50 on his Outrage 18 and it seems to perform well.
I think the very obvious thing to do in this case is to try it. You already own the 18' hull and the motor, so it's a no brainer.
No, you do not need to sit on the transom to steer, you just install a simple pedestal seat to steer from. This setup is VERY common in British Columbia among the fishing guides.
Dave Sutton posted 03-02-2011 07:53 PM ET (US)
None. It's not the right engine for *any* Whaler.
Sell the engine and buy a boat that you want. Selecting a boat to fit an orphan engine is really putting the cart before the horse.

Dave
.
Tom W Clark posted 03-02-2011 08:09 PM ET (US)
Mike -- With a 13-1/4" x 13" Stiletto Advantage, your F70 powered Guardian 18 should be good for about 30-32 MPH.
towboater posted 03-03-2011 03:29 PM ET (US)
Ophan engine.
Hehe, I like that one.
I agree with Dave Sutton,
It appears to be true that NO WHALER will "easily" adapt to a 70hp 4 stroke engine.
Im not sure if I have the cart before the horse...that engine cost $9.5k with tiller, a used whaler hull between 15-18 ft is less...hard to find but they are out there.
I have $4.5k invested in my salvaged Guardian and very nice OEM trailer over the past 3 years.
I will argue a CPD hull is FAR better ride and more rugged than typical aluminum hull sport boats of similar size.
3 months ago I purchased a 04, 24 ft Maxweld alum hull console boat that is best described as a TANK. It was the personal boat of the former owner of Maxweld. Maxweld only builds custom order boats...they are very rare. Ive even considered using the F70 as a kicker for this boat.
The console is welded to the deck, to give you an idea how strong this guy built the boat, the alum bimini top has a tow post for pulling wakeboards. Hull is semi deep V, reverse chine, which is also very rare and expensive alum option. It is a head turner...every weld is a work of art.
My allegeance to Whaler goes back to 71, Prince William Sound, Valdez Alaska. As a fishing guide, I had my choice of 14 boats and preferred the Whaler with Evinrude tiller on nice days. Must have been a Montauk equivalent. The F70 and Guardian are paid for, now melting. Mounting the F70 with tiller on the 18 is a no brainer, Im not looking for style points here but 20" shaft and 25" transom conflict. I guess I could offset the engine to one side and put a 25 gal fuel tank/seat on the other...
Plan C is to mount the F70 on 28 x 12 flat wood deck and steel pontoon work float and sell the Guardian. I need to change my username to "indecision".
Peter posted 03-03-2011 03:35 PM ET (US)
$9.5k with a tiller? Yikes! Before the 70 2-stroke was discontinued, it was about $5K to $5.5K brand new.
towboater posted 03-03-2011 10:40 PM ET (US)
Price included Wa sales tax, tiller, old engine removed and loaded in the back of my pickup, new engine installed, 2 props, 2 oil change kits, gear lube and some other stuff.
My crew boat needed a plug and play motor in a hurry, I didnt dicker with pricing, time was a far bigger factor. Compared to down time losses, the discount you refer to is peanuts. This whole deal took 1 day, IMO, they earned their profit.
And here I sit with a orphan motor trying to figure out what to do with it.
mk
Tom W Clark posted 03-03-2011 11:30 PM ET (US)
Mike -- I still say bolt it onto the Guardian hull and see how it does. It is an almost trivial rigging chore; just four bolts, get a battery and fuel tank and away you go for testing.
If it doesn't work, it was a good try and if it does, you have an awesome fishing skiff.
As I pointed out, a 20" shaft length Yamaha (of far lesser horsepower) has been fitted to this hull before:
http://continuouswave.com/ubb/Forum4/HTML/007240.html
number9 posted 03-03-2011 11:39 PM ET (US)
Mike,
I'm the one with the T50 on my 18' Outrage. Only small downside is it will ventilate in a sharp turn at top speed unless throttle reduced a bit. No need to offset the F70. The distance between the motor mounting bracket and the AV plate is 21" according to Yamaha. MY AV plate is approx 3.5" above the bottom. It works because of the vee-hull stern deadrise. Amazing but true.
Bill
towboater posted 03-04-2011 05:29 AM ET (US)
OK Tom & Bill & everyone, thanks, proceeding with confidence. Willapa Bay tide flats, Long Island steamer clams...here I come.
With the Mill shut down til Mar 28 to "re-tool" the Peco crane with new drives, I have time to kill.

How to tow 18 ft Guardian on a OEM trailer, upside down, 100 miles:
I have a boom truck and had no problem lifting it off the trailer, flipping upside down and setting back down on timbers with the Military console and tow bit in tact.
For 2 years now I have meticulously patched and sanded, patched and sanded two pretty bad holes, weather permitting. So finally frustrated with the weather (this is a dusty area) and wanting a decent barrier coat I started trying to figure out how to place the boat on the trailer upside down and take to my Dads garage 100 miles away.
The gunwales need to be approx 18" above the trailer frame.
Laminating lumber across the frame 18" isnt as easy as it sounds to make it secure and stable. Securing a 18" dia log across the front of the trailer is easy enough, placing a log across the back so the towbit wouldnt ding the perfect rollers and bunks isnt so easy.
YESTERDAY, it hit me;
God made rubber tires for Tugboats and boat trailers.
I feel like a fool it has taken me so long to figure this out.
deepwater posted 03-05-2011 10:53 AM ET (US)
They also make inner-tubes that when placed between 2 large sections of plywood make a great temp air jack,,It will slip under something as close to the ground as 2" and lift 8"

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Author	Topic: Best Hull for a Yamaha F70 Tiller
towboater	posted 02-25-2011 01:24 PM ET (US) What classic [Boston] Whaler hull would be best suited for a single [Yamaha] F70, 257-lbs, 20-inch leg, with tiller? I am aware of the Sport model but seems like there is another better suited. I[']ve given up trying to find time to finish restoring a [1987] Guardian 18 hull and mount twin F70's. How I ended up with a single 2010 low[-hour] F70 sitting [on] a bench is a long story.--Mike
Tohsgib	posted 02-25-2011 01:33 PM ET (US) Your 18 will move Ok with a 70 but a 15/17 would be better. Can you convert to remote or tiller only? In Belize our guide had twin Johnson 65hp commercial pull start tillers. They were connected with a rope so the props would not hit. He would stand between them and steer/throttle with each hand, you don't see that too often in the States.
towboater	posted 02-25-2011 02:29 PM ET (US) Thx Mr Big. F70 is only 20" shaft. Im sure the 70 would bring it up on step but thats about it. Im not in a big hurry. Time to kill today, mulling options. I guess I could trade in the 70 for a 90 for very close to the same cost as selling the 18 and purchase a decent 15/17 hull, blown motor and worn out helm... mk
littleblue	posted 02-26-2011 02:28 PM ET (US) Best? Gotta be the 15. The motor would work well on a Montauk too. New twin F70's on the 18 would be coolest though. :)
Peter	posted 02-26-2011 02:58 PM ET (US) A 70 HP tiller operated motor on a 15 that has a tendency to chine walk above 39 MPH would be dangerous and probably not recommended by Whaler.
Tohsgib	posted 02-28-2011 10:54 AM ET (US) Considering it says in the brochure that 40hp is max on a tiller 15 and 50 on a 17' I would agree with you but it would be fun and if you set it up correctly it will not porpoise or chine walk. None of my 15's started to walk until about 44 or so.
dgoodhue	posted 02-28-2011 12:08 PM ET (US) Without a Jackplate and having the ablilty to trim the motor out, a 15' with 70hp will not be chinewalking. My 15' does about 41-42mpg before I trim out the motor out. I suspect the jackplate I have add a few mph to my top end as well. The motor might rip out of your hand on the hole shot or knock you over board if standing.
Tohsgib	posted 02-28-2011 03:36 PM ET (US) Mine as well. She would start walking from about 43ish to 48+ WOT trimmed out shouting a 6' high rooster tail. Still was not bad until you tried to turn. You would bang back the throttle and nail it again to stop the walking...temporarily of course....fun boat.
Tohsgib	posted 02-28-2011 03:38 PM ET (US) Actually there is a guy on here with a 50(20") on a 18 and he says she runs like 28. A 70 I would think would do 32+ but you would need a 8-10" setback jackplate to run that 20" and with a tiller you would be sitting on the transom..literally.
towboater	posted 02-28-2011 05:57 PM ET (US) Thanks. Yeah, 45 in a open 15 ft boat would be fun. Ass cheeks on the spash well isnt. You guys have convinced me I should go back to square one, mount the 70 on the 28 x 12 work float until the Guardian is done, then go with twins and push the work float around with that...or I might even play a little. One thing I have learned, searching boat sales sites almost daily for a Whaler with worn out engine and helm...there arent any. Im not married to or fanatical about Whalers, but I am convinced, Whaler owners seem to be more concientious about boats and maint than the average bears. Mike
Binkster	posted 03-01-2011 09:04 AM ET (US) I don`t think any Whaler will give you the adrenaline rush you are seeking. Get something like this. tiller motors are a simple way to have fun. http://www.youtube.com/watch?v=O_KR4Uv9NM0&NR=1
Tom W Clark	posted 03-02-2011 02:31 PM ET (US) Mike, I would not put a new F70 tiller on a 15' hull. The combination of a relatively heavy motor combined with a seating position so close to the stern would result in a very stern heavy condition. The 15' hull is only rated for 40 HP in tiller steering configuration. The 16'-7" hull would be a better choice. Though it is only rated for 50 HP with tiller steering (the Guardian 17 is rated for 55 HP), I suspect it would be fine. The Outrage/Guardian 18/19 has a minimum power rating of 75 HP, though a new F70 might be adequate. The more limiting factor here is the 20" shaft length of the motor for a boat that is designed for a 25" shaft length motor. However, as Nick points out, Bill (number9) has a 20" Yamaha T50 on his Outrage 18 and it seems to perform well. I think the very obvious thing to do in this case is to try it. You already own the 18' hull and the motor, so it's a no brainer. No, you do not need to sit on the transom to steer, you just install a simple pedestal seat to steer from. This setup is VERY common in British Columbia among the fishing guides.
Dave Sutton	posted 03-02-2011 07:53 PM ET (US) None. It's not the right engine for any Whaler. Sell the engine and buy a boat that you want. Selecting a boat to fit an orphan engine is really putting the cart before the horse. Dave .
Tom W Clark	posted 03-02-2011 08:09 PM ET (US) Mike -- With a 13-1/4" x 13" Stiletto Advantage, your F70 powered Guardian 18 should be good for about 30-32 MPH.
towboater	posted 03-03-2011 03:29 PM ET (US) Ophan engine. Hehe, I like that one. I agree with Dave Sutton, It appears to be true that NO WHALER will "easily" adapt to a 70hp 4 stroke engine. Im not sure if I have the cart before the horse...that engine cost $9.5k with tiller, a used whaler hull between 15-18 ft is less...hard to find but they are out there. I have $4.5k invested in my salvaged Guardian and very nice OEM trailer over the past 3 years. I will argue a CPD hull is FAR better ride and more rugged than typical aluminum hull sport boats of similar size. 3 months ago I purchased a 04, 24 ft Maxweld alum hull console boat that is best described as a TANK. It was the personal boat of the former owner of Maxweld. Maxweld only builds custom order boats...they are very rare. Ive even considered using the F70 as a kicker for this boat. The console is welded to the deck, to give you an idea how strong this guy built the boat, the alum bimini top has a tow post for pulling wakeboards. Hull is semi deep V, reverse chine, which is also very rare and expensive alum option. It is a head turner...every weld is a work of art. My allegeance to Whaler goes back to 71, Prince William Sound, Valdez Alaska. As a fishing guide, I had my choice of 14 boats and preferred the Whaler with Evinrude tiller on nice days. Must have been a Montauk equivalent. The F70 and Guardian are paid for, now melting. Mounting the F70 with tiller on the 18 is a no brainer, Im not looking for style points here but 20" shaft and 25" transom conflict. I guess I could offset the engine to one side and put a 25 gal fuel tank/seat on the other... Plan C is to mount the F70 on 28 x 12 flat wood deck and steel pontoon work float and sell the Guardian. I need to change my username to "indecision".
Peter	posted 03-03-2011 03:35 PM ET (US) $9.5k with a tiller? Yikes! Before the 70 2-stroke was discontinued, it was about $5K to $5.5K brand new.
towboater	posted 03-03-2011 10:40 PM ET (US) Price included Wa sales tax, tiller, old engine removed and loaded in the back of my pickup, new engine installed, 2 props, 2 oil change kits, gear lube and some other stuff. My crew boat needed a plug and play motor in a hurry, I didnt dicker with pricing, time was a far bigger factor. Compared to down time losses, the discount you refer to is peanuts. This whole deal took 1 day, IMO, they earned their profit. And here I sit with a orphan motor trying to figure out what to do with it. mk
Tom W Clark	posted 03-03-2011 11:30 PM ET (US) Mike -- I still say bolt it onto the Guardian hull and see how it does. It is an almost trivial rigging chore; just four bolts, get a battery and fuel tank and away you go for testing. If it doesn't work, it was a good try and if it does, you have an awesome fishing skiff. As I pointed out, a 20" shaft length Yamaha (of far lesser horsepower) has been fitted to this hull before: http://continuouswave.com/ubb/Forum4/HTML/007240.html
number9	posted 03-03-2011 11:39 PM ET (US) Mike, I'm the one with the T50 on my 18' Outrage. Only small downside is it will ventilate in a sharp turn at top speed unless throttle reduced a bit. No need to offset the F70. The distance between the motor mounting bracket and the AV plate is 21" according to Yamaha. MY AV plate is approx 3.5" above the bottom. It works because of the vee-hull stern deadrise. Amazing but true. Bill
towboater	posted 03-04-2011 05:29 AM ET (US) OK Tom & Bill & everyone, thanks, proceeding with confidence. Willapa Bay tide flats, Long Island steamer clams...here I come. With the Mill shut down til Mar 28 to "re-tool" the Peco crane with new drives, I have time to kill. How to tow 18 ft Guardian on a OEM trailer, upside down, 100 miles: I have a boom truck and had no problem lifting it off the trailer, flipping upside down and setting back down on timbers with the Military console and tow bit in tact. For 2 years now I have meticulously patched and sanded, patched and sanded two pretty bad holes, weather permitting. So finally frustrated with the weather (this is a dusty area) and wanting a decent barrier coat I started trying to figure out how to place the boat on the trailer upside down and take to my Dads garage 100 miles away. The gunwales need to be approx 18" above the trailer frame. Laminating lumber across the frame 18" isnt as easy as it sounds to make it secure and stable. Securing a 18" dia log across the front of the trailer is easy enough, placing a log across the back so the towbit wouldnt ding the perfect rollers and bunks isnt so easy. YESTERDAY, it hit me; God made rubber tires for Tugboats and boat trailers. I feel like a fool it has taken me so long to figure this out.
deepwater	posted 03-05-2011 10:53 AM ET (US) They also make inner-tubes that when placed between 2 large sections of plywood make a great temp air jack,,It will slip under something as close to the ground as 2" and lift 8"