mid range twins...

[Sean C.]

Bob, I re-read what I wrote and didnt mean to make it sound like an attack on what you had to say. I think diesel is the ideal choice for anything, its just not always practical either financially or mechanically. I also personally like a full displacement trawler, but then again I have a certain spot in my heart for all types of boats. Part of my sales pitch on outboards, especially the 4 strokes, is that they are designed around operating at their maximum RPM (approximately 6000) continuously. There absolutely is a right motor/drive combo for every application. I know you werent trying to sway Todd away from outboards, nor is it my agenda to sway him to outboards. We are all here to help each other out and share out expertise.

Regards,

Sean

 

[Bob B]

No attack felt, just some winded clarification on my part to start the long off season.
I am going to pick up the revised tolman book, as I only have the orig.
I think you will understand my line of thought if you get the time to read the link.
When I wanted to build the 18 way back, all I had was a 25 and it would have pushed it, but slow. I ended up with a 16 foot flat bottom dory to get more speed. Now with three kids I need a 26, but still only own a 25hp. Oh well, slow it is for me. But if speed is desired, small motors working in the upper limits of their torque curve are going to hate life, if they dont have what the hull requires at the speed range desired.
I dont have the weight or hull shape info to run it, but that will get done.
What was the operating profile of your work boat? I think of continous in terms of 24-7, not 8 and out. 6000rpm is fast for 24 7 but fine as you experienced, and I dont think most rec opperators will run more than 4 to 6 a day. Most marine motors die from external block component failure due to maint issues, but overloaded motors are the number one cause of piston failure.

 

[tod osier]

Hey Guys, thanks for all the ruminating on my behalf. As far as a single motor and a kicker, that isn't out, BUT...

I understand that a single 60 is unlikely to get the boat on plane, but there is also no way I'd be comfortable offshore (10-15-20-30-40-50-60 miles out) with a 10 hp kicker, it may be a fine backup in typical conditions inshore. As Sean says, there is no way in hell a kicker is going to get you home from offshore on the day that you have a motor malfunction and NOAA was wrong about the 5-10 knots and it is 15-20 with gusts to 30 (not that THAT EVER HAPPENS). The cost of an offshore tow is scary, I can't imagine how lonely it would be sitting dead in the water on a sea anchor waiting for them to show up.

I thought about the diesel, but the trailering issue and just the trouble of setup and cost, pretty much killed that.

As far as the boat, with the flexibility in designs, I'm sure I can come up with what will work, I want a small cabin for a head with a hard top to get out of the sun. An truely offshore capable boat may be a little far fetched, but there is no question I'll be doing some baby offshore, like tuna and groundfish off Cape Cod. I haven't looked at what people typically get out of the Tolmans, but there is a lot of latitude to play with weight and hull length/width. They are fairly light boats, so going like a raped ape wouldn't be a good option other than on the rare calm days anyway.

T

 

[Scott Farris]

Tod,

Just in case we haven't discussed this yet, don't forget fuel consumption. MPG off plane is significantly higher than on. Just make sure your fuel cap Vs one motor return works out. The couple of guys who rigged twins for the run to the canyon selected the smallest motor that would get them on plane then doubled it. The boats just didn't have the fuel margin to reliably come back home off plane after a day of fishing. On plane no problem. Plus they could duck into Montauk for a drink if it got too hairy.

Scott

 

[TimJ]

My $.02 but I'd pass on twins who weigh in at over 450, nothing mid range about 'em.... and since you are married and all I think it's a no brainer for you.

Oh come on, we can't have a topic like "mid range twins..." not have a joke in it.

Tim

 

[tod osier]

Tod,

Just in case we haven't discussed this yet, don't forget fuel consumption. MPG off plane is significantly higher than on. Just make sure your fuel cap Vs one motor return works out. The couple of guys who rigged twins for the run to the canyon selected the smallest motor that would get them on plane then doubled it. The boats just didn't have the fuel margin to reliably come back home off plane after a day of fishing. On plane no problem. Plus they could duck into Montauk for a drink if it got too hairy.

Scott

Scott,

I'm not sure I'm buying what you are selling. If you are coming back off plane, you would be at significantly lower RPMs on one engine, it isn't like you would be running at full throttle to get to hull speed. Fuel consumption increases dramatically at high RPM, putting back at hull speed would take a tiny fraction of what it would to keep up on plane. Speed per speed consumption woudl be higher off plane than on (if that is possible), but putting at hull speed is way more efficient than zipping along at cruising speed. I'm I wrong on this?

Plus, if you have an engine down, you could steal from the top of your second tank.

T

 

[tod osier]

My $.02 but I'd pass on twins who weigh in at over 450, nothing mid range about 'em.... and since you are married and all I think it's a no brainer for you.

Oh come on, we can't have a topic like "mid range twins..." not have a joke in it.

Tim

Don't think it didn't cross my mind.

 

[Scott Farris]

Tod,

I'm passing on what I was told and it seems to make sense that on plane your on top of the water not pushing it out of the way like a displacement hull. Fuel consumption may be up with the bigger motor on plane but distance traveled is farther (say 2.5 to 3 X as far) than the smaller motor to push / plow you along against the hull speed. What is the true hull speed of the boat? I know our 33' sail boat was 6 - 6.5 knots while the 50 footer was 7.5 k. If your happy with the 5 or 6 mph you don't need the 60 hp. If you want to take advantage of the 60 horses and push along at 10 or 12 mph, your outboard will be sucking fuel.

or GPM of 90 hp on plane > GPM of 60 plowing But MPG of 90 hp on plane < MPG of 60 plowing

Hopefully others with real practical experience will share.

Scott

 

[tod osier]

Tod,

I'm passing on what I was told and it seems to make sense that on plane your on top of the water not pushing it out of the way like a displacement hull. Fuel consumption may be up with the bigger motor on plane but distance traveled is farther (say 2.5 to 3 X as far) than the smaller motor to push / plow you along against the hull speed. What is the true hull speed of the boat? I know our 33' sail boat was 6 - 6.5 knots while the 50 footer was 7.5 k. If your happy with the 5 or 6 mph you don't need the 60 hp. If you want to take advantage of the 60 horses and push along at 10 or 12 mph, your outboard will be sucking fuel.

or GPM of 90 hp on plane > GPM of 60 plowing But MPG of 90 hp on plane < MPG of 60 plowing

Hopefully others with real practical experience will share.

Scott

Scott,

In my understanding and experiance, you aren't going to make a 20'+ boat go 10-12 unless you are on plane. If your buddies were getting 10-12 knots, they had the hull on plane , maybe poorly, but on plane and were sucking the fuel down as a result. You are right that you wouldn't need a 60 to keep a boat like the tolman at hull speed, but to do it with authority in big swells, with wind and current, what would you need? I don't think a 10 would cut it. So what would you need a 15, a 20? Sean did a calcualtion on price and weight and twins won vs a single and a 10 hp kicker, a 15 or 20 would be worse.

The other thing that for me where twins kicks a kicker's ass is that a kicker suffers for disuse unless you are a troller. Little use is never a good thing for reliability. We both have backup kickers for our boats - neither are hardly broken in and hardly ever run. I make it a point to run mine for 30 minutes a year, not exactly a lot of running.

I'm assuming you haven't ever run your Lund in nasty weather with your kicker. That would eb some good info on how it did, if you had.

 

[Matthew R. Snyder]

I understand that a single 60 is unlikely to get the boat on plane,

You sure about that? No first-hand familiarity with the Tolman hull design but I have seen some damn big hulls moved around nicely by single, small-displacement two strokes.

There's a place where we hunt where guys run open aluminum scows ranging from 20-24 feet for trotlining and eel netting. They all run Yam C40s and don't have any trouble planing, they are just slow.

Same token I have seen more than a few Lund 20s with 50 hp motors -- a few dealers like to sell 'em that way to guys who can't also afford a nice new 115. I don't think it'll carry much of a load but they do plane out.

Tolman would be a lot heavier and draggier but still, bigger boats than that have been planed with a single, midrange outboard.

Here's some more food for thought: for what you want to do the old four-vs.two-stroke debate might actually be meaningful. I'm just picking Yam because I'm most familiar with their products:

The Yamaha f60 four stroke is 237 lbs., times two is 474.

The Yamaha two-stroke 70 is 228 lb.; total weight would be 18lb. LESS than twin f60 four strokes.

And having run both the f60 and the 70TRX on identical boats, I can report that the 70 TRX has a LOT more balls than the f60, all out of proportion to what looks like a relatively modest increase in rated hp. Burns a lot more gas, too, but it's a stone reliable motor if you take care of it.

Move up the scale even further, the Yamaha two-stroke 90 is 261; total weight compared to the f60 would be 48 lb. more, but I bet 50 extra pounds off the stern of a 22' boat won't mean too much, and then you would have more confidence to move the boat decently with just one motor, without fear of lugging it at low rpms (and grenading under the strain).

As to your last question, I have run a Lund 18 with a kicker (8 hp) in poor weather, just to see how it would do. I didn't really like it. I could keep it from wallowing in the trough just fine, I could heave to without dying, but i did NOT trust its ability to bring the head up into a big sea. Based on that (limited) test, I have never since carried a kicker as its extra weight, inconvenience, and risk of it getting me halfway out of a jam outweigh its benefits for me.

 

[Eric Dellamater]

I understand that a single 60 is unlikely to get the boat on plane,

You sure about that? No first-hand familiarity with the Tolman hull design but I have seen some damn big hulls moved around nicely by single, small-displacement two strokes.

yes.....that is from guys who have Tolman's and are running them out on the West coast. I want to point out Todd is talking about a Jumbo, not the widebody or the standard. Depending on length, Renn Tolman the designer spec's 90 -115-140 as his recommendations. Todd, build it, run the twins and let all the Tolmanites and others see how well it works, guys talk about it, but then back off. I would be interested in seeing it done. I understand your desires for redundancy, but I am nagged by the guys in Alaska who mention doing 100 mile trips in a day with a susuki 140 fairly frequently. Heck, read about Renn doing his trip to Homer which was like 200+ miles with over 100 of it in open unprotected waters. I just wonder if it is worth the effort...I bet I would like it if truly stranded. What do you think about my questions of over revving the one engine and prop sizes? Anyone?

 

[Sean C.]

A couple of other things to mention as well: One is that with mid-range twins you have two rudders in the water, so at a "no wake" speed your ability to turn the boat quickly increases dramatically. To go along with the two rudders (this has probably been mentioned previously) but you have the ability to spin your boat in its own length (if that ever were to peak your interest).

As for trolling, a 60hp Yamaha runs smoother, quieter, and more fuel effecient than any small kicker motor in my opinion, whether it be at an idle or full throttle. If you are trolling at 2-3 knots I would bet you would see no difference in fuel consumption between a 4 stroke kicker motor and a 60hp 4 stroke. If you plan on fishing for tuna, a 10hp kicker would not even push the boat fast enough! When i'm fishing for Albacore we troll between 6 and 8 knots over the ground. So if you had a large main/kicker set up you would have to be trolling with your large main anyway. With the twins, you could alternate which motor you trolled with, keep the total hours down overall, and then like Tod said your not letting the kicker just sit until an emergency at which point the darn motor doesnt start from lack of use.

 

[Sean C.]

I completely forgot about this boat, but I sold Devlin a 60hp Yamaha for a 22' tug/cruiser he build this past summer. The boat is mostly flat bottomed (very slight v to it) I would say weighs around 3000lbs total, and the boat did 12-14 knots at WOT. The link is http://devlinboat.com/...tacoma%20narrows.jpg to a picture of the boat. This might answer many questions that have been asked, and maybe some that have not been asked. My experience is that the 50/60 hp Yamaha will burn 4-5 gph at WOT, and far less if you back off to 4500 rpm.

The Yamaha 2 stroke 70 and 90 hp are being discontinued. They are extremely light for their hp and are great on certain applications. But you still have a carburated 2 stroke that is sucking down some serious fuel (in comparison to a 4 stroke) and oil that now costs $25 per gallon.

Full story on this 22' Devlin is at http://devlinboat.com/32nd_WBF.htm

 

[tod osier]

I understand that a single 60 is unlikely to get the boat on plane,

You sure about that? No first-hand familiarity with the Tolman hull design but I have seen some damn big hulls moved around nicely by single, small-displacement two strokes.

There's a place where we hunt where guys run open aluminum scows ranging from 20-24 feet for trotlining and eel netting. They all run Yam C40s and don't have any trouble planing, they are just slow.

Same token I have seen more than a few Lund 20s with 50 hp motors -- a few dealers like to sell 'em that way to guys who can't also afford a nice new 115. I don't think it'll carry much of a load but they do plane out.

Tolman would be a lot heavier and draggier but still, bigger boats than that have been planed with a single, midrange outboard.

Here's some more food for thought: for what you want to do the old four-vs.two-stroke debate might actually be meaningful. I'm just picking Yam because I'm most familiar with their products:

The Yamaha f60 four stroke is 237 lbs., times two is 474.

The Yamaha two-stroke 70 is 228 lb.; total weight would be 18lb. LESS than twin f60 four strokes.

And having run both the f60 and the 70TRX on identical boats, I can report that the 70 TRX has a LOT more balls than the f60, all out of proportion to what looks like a relatively modest increase in rated hp. Burns a lot more gas, too, but it's a stone reliable motor if you take care of it.

Move up the scale even further, the Yamaha two-stroke 90 is 261; total weight compared to the f60 would be 48 lb. more, but I bet 50 extra pounds off the stern of a 22' boat won't mean too much, and then you would have more confidence to move the boat decently with just one motor, without fear of lugging it at low rpms (and grenading under the strain).

As to your last question, I have run a Lund 18 with a kicker (8 hp) in poor weather, just to see how it would do. I didn't really like it. I could keep it from wallowing in the trough just fine, I could heave to without dying, but i did NOT trust its ability to bring the head up into a big sea. Based on that (limited) test, I have never since carried a kicker as its extra weight, inconvenience, and risk of it getting me halfway out of a jam outweigh its benefits for me.

Matthew,

Darn, lost my reply... Anyway, great info, very helpful... On the kicker that is what I'm worrying about, the Tolman would be a lot heavier than an 18' lund. It woudl also be a lot higher sided and have a cabin, so it woudl be more like a sail and need more power to fight the wind.

I believe that a 2 stroke yamaha 70 puts a whoopin on an F60. I love my F40, but the last thing I would call it is a powerhouse.

I haven't thought about 2 strokes - they do make sense, but I can't see myself buying one (or two) for a number fo reasons. Your calculations are right on if a 2 stroke was in the running.

 

[tod osier]

I understand that a single 60 is unlikely to get the boat on plane,

You sure about that? No first-hand familiarity with the Tolman hull design but I have seen some damn big hulls moved around nicely by single, small-displacement two strokes.

yes.....that is from guys who have Tolman's and are running them out on the West coast. I want to point out Todd is talking about a Jumbo, not the widebody or the standard. Depending on length, Renn Tolman the designer spec's 90 -115-140 as his recommendations. Todd, build it, run the twins and let all the Tolmanites and others see how well it works, guys talk about it, but then back off. I would be interested in seeing it done. I understand your desires for redundancy, but I am nagged by the guys in Alaska who mention doing 100 mile trips in a day with a susuki 140 fairly frequently. Heck, read about Renn doing his trip to Homer which was like 200+ miles with over 100 of it in open unprotected waters. I just wonder if it is worth the effort...I bet I would like it if truly stranded. What do you think about my questions of over revving the one engine and prop sizes? Anyone?

It comes down to your acceptance of risk. I've seen 20' open runabouts I/Os 60 miles offshore with several barrels of gasoline in the cockpit in 8' seas trollingn for tuna.

There are a couple Jumbos with twin 90's.

 

[tod osier]

I understand that a single 60 is unlikely to get the boat on plane,

You sure about that? No first-hand familiarity with the Tolman hull design but I have seen some damn big hulls moved around nicely by single, small-displacement two strokes.

yes.....that is from guys who have Tolman's and are running them out on the West coast. I want to point out Todd is talking about a Jumbo, not the widebody or the standard. Depending on length, Renn Tolman the designer spec's 90 -115-140 as his recommendations. Todd, build it, run the twins and let all the Tolmanites and others see how well it works, guys talk about it, but then back off. I would be interested in seeing it done. I understand your desires for redundancy, but I am nagged by the guys in Alaska who mention doing 100 mile trips in a day with a susuki 140 fairly frequently. Heck, read about Renn doing his trip to Homer which was like 200+ miles with over 100 of it in open unprotected waters. I just wonder if it is worth the effort...I bet I would like it if truly stranded. What do you think about my questions of over revving the one engine and prop sizes? Anyone?

If you lost a motor, you would be over propped on the remaining. That would not be a problem for the few hours that you were driving at hull speed back in.

 

[Matthew R. Snyder]

The Yamaha 2 stroke 70 and 90 hp are being discontinued. They are extremely light for their hp and are great on certain applications. But you still have a carburated 2 stroke that is sucking down some serious fuel (in comparison to a 4 stroke) and oil that now costs $25 per gallon.

Son of a bitch! When? And why, because of CARB compliance bullshit?

Pushing a big, heavily loaded boat across big water, into very skinny water, happens to be one of those "certain applications" and the two strokes have worked out better than the four strokes... I like four strokes a LOT for every application except that one, but for that one, the two strokes really shine. And last.

 

[Brad Bortner]

Todd

Not to hijack your thread, but how about some pictures of your Tolman?

 

[Ben Gallop]

From running multiple boats with large twin outboards and fuel consumption meters along with calculating the gallons per mile, your cruising RPM will give you the best gallons per mile. Being on a plane greatly reduces fuel consumption when compared with distance until you push it past the cruising RPM. Then it goes downhill fast. Of course, gallons per hour are going to be a lot less at lower RPMs. My experience is from running twin 200hp or 250hp 65 miles offshore and trolling for 8-10 hours. You burn your fuel faster going in and coming out than you do trolling, but you cover a whole lot more ground.

Of course, I am not familiar with a Tolman skiff's planing abilities. If it doesn't plane it won't matter. If it does plane, it will likely get better mileage on a plane.

I've also seen gas consumption dramatically increase when a boat with twins has to come home on one of them alone. You want to be able to plane out, if of course the boat is a planing hull.

Another thing, I have seen folks use kickers as backup on 22-24ft Grady Whites and such. No chance of them planing, but the kicker will get you back to shore (although power is king when your in the inlet).

When I worked at a marina some folks came in there one day with a 40ft two story houseboat that had a 35hp inboard/outboard. With the right man behind the wheel, it was manueverable even in a wind. The folks driving it were not the "right man" though. Luckily, we had a local guy who hopped on board befoIre they tore any other boats up. I don't think it would plane though.

I've got a 70hp 4 stroke suzuki on my 18' C-Hawk which I believe weighs 2000+ pounds. It gets on a plane good and it runs well with a load. It just never goes real fast. How much more than that would your Tolman weigh?



Probably doesn't help, but that's my experience...

 

[harry whitley]

Years ago I had the opportunity to con a boat that had twin Johnson 35's. Had to keep both hands on the wheel at all times. Backing the boat was a breeze and the added insurance of two motors was great back then. Today's motors are much more reliable regardless of flavor.

I might go with a higher horsepower engine for your V hull like maybe a 70 and add a kicker on one of those transom thingies as a get home or trolling motor.

You have had some great advice from most of the members. Had never heard of an outboard described as a "hand grenade". Having tossed a few real grenades myself, I just don't see a comparrison. Also the cost of diesel fuel would preclude it for my use.
JMO,
Harry