Hard Chined Square Assed Boats

John,
I thought about it some and you may be right but I think it has more to do with speed. Almost all full disp hulls are limited to hull speed. At times when I leave the harbor and rev up to " cruising " speed I look at the water and can't belive how slow I'm going. Most guys just couldn't stand it. Takes us almost a full working day to get to Ketchikan .. but it takes only 5 gal. The ferry fare is now $100. RT one person so we go much cheaper on the Willard and then we stay on the boat and save $100 a day there too. But it takes two days to come and go. With your Mainship we could come and go in the same day but it would probably cost more in fuel than the ferry. There are some boats that function as a disp hull at disp speeds and at semi disp speeds they are much more effiencent than TTs, Nordics, GBs and the like. These boats were designed by William Hand about 1910 when engines were very low on power. They switch roles by taking advantage of the change in pitch attitude. Google search South Hampton Marine or Handy Billy to see a modern version of his hull form. Brilliant design. BUT .. these boats will not plane above a SL ratio of about 2.25 .. about 12 knots for a 32' boat. These are the kind of boats I predict will emerge on the market but not untill fuel gets more dear. As is obvious from earlier discussion, box style hulls will prevail a bit longer.

Eric Henning
Willard 30
Thorne Bay AK

Our boat is a hard chined, square ass semi-displacement hull that cruises at 8.5 knots. I'm always asking, "are we there yet?" After eight years of this, I still look back with fond memories when we had a planing hull and scooted along at 16 knots. If I could afford the fuel, I would not hesitate to go back to a fast cruising boat. To me, getting there is not half the fun.

Well, everyone has different priorities. While I enjoy running around in the Broughtons or wherever in our 17' Arima at close to 30 mph, I also enjoy long runs in our 8-knot GB. As it is in the floatplane and the narrowboat in the UK, to me ALL the fun is in the getting there. I'm always rather disappointed when the journey ends and we arrive at our destination. While the locations we visited on our recent three-week trip to Desolation Sound were enjoyable, the most fun I had on the trip were the journeys between them, particularly the five, six, and seven hour runs. I just like moving on the water. To me, the time spent at anchor or at a dock is just the price I have to pay for being able to take another run the next day

nomadwilly wrote:

John,
I thought about it some and you may be right but I think it has more to do with speed.

Eric Henning
Willard 30
Thorne Bay AK

Click to expand...

Eric, if you noticed I said stability was the reason that semi boats were powered with engines that were only able to do displacement speeds.* FF always scratched his head wondering why the hell they would build a semi boat and then put small engines in it.* Stability is one of the main reasons as is space.

As for going fast in general, we actually miss going slow.* The fun really is in the journey.* When you have a faster boat, the boat basically becomes an instrument of your getting from point A to point B with that is the sole goal.* When you go slow, you settle into a rhythm of the lifestyle of cruising.* You kow you are gonna be on the boat all day so you set up your "lifestyle" to do that.* Whereas on the go fast, you just throttle up and point the nose and sit there ans watch out for stuff.*

I've gone fast (20+) for most of my boating life. It's only in the last 2 years or so that I've experienced the 8.5kt. cruise and I just love it! Oh, my boat will go faster (but not much) but the economy just isn't there. The noise is louder, the ride is bumpier, and my wife does not feel threatened when she has the con at 8.5 knts. The real payoff for me, however, is hanging on the hook for a day or two. Man, what a feeling! The boat is working great, we're super comfortable, my big ass anchor isn't dragging, the frig and icemaker are working off the inverter, life is good! I can think of only one thing better in this life but can't comment on it in much detail here. (But that, too, can be experienced when on the hook.)

-- Edited by SeaHorse II at 15:05, 2008-09-27

Baker wrote:
nomadwilly wrote:

John,
I thought about it some and you may be right but I think it has more to do with speed.

Eric Henning
Willard 30
Thorne Bay AK

Click to expand...

Eric, if you noticed I said stability was the reason that semi boats were powered with engines that were only able to do displacement speeds.* FF always scratched his head wondering why the hell they would build a semi boat and then put small engines in it.* Stability is one of the main reasons as is space.

As for going fast in general, we actually miss going slow.* The fun really is in the journey.* When you have a faster boat, the boat basically becomes an instrument of your getting from point A to point B with that is the sole goal.* When you go slow, you settle into a rhythm of the lifestyle of cruising.* You kow you are gonna be on the boat all day so you set up your "lifestyle" to do that.* Whereas on the go fast, you just throttle up and point the nose and sit there ans watch out for stuff.*


90% of the fun going by boat is the boat ride, every time I go some place and get tied up my next step is to jump in the dinghy and go for another boat ride!

Walt
"but that too can be experienced on the hook"; "Luck is being prepared for opportunity"

You might be surprised in a secluded waterway, while going slow and not having to look out for every floating limb....
"Man what a feeling"!

Just some random quotes, of course

troy994719 wrote:
Baker wrote:
nomadwilly wrote:

John,
I thought about it some and you may be right but I think it has more to do with speed.

Eric Henning
Willard 30
Thorne Bay AK

Click to expand...

Eric, if you noticed I said stability was the reason that semi boats were powered with engines that were only able to do displacement speeds.* FF always scratched his head wondering why the hell they would build a semi boat and then put small engines in it.* Stability is one of the main reasons as is space.

As for going fast in general, we actually miss going slow.* The fun really is in the journey.* When you have a faster boat, the boat basically becomes an instrument of your getting from point A to point B with that is the sole goal.* When you go slow, you settle into a rhythm of the lifestyle of cruising.* You kow you are gonna be on the boat all day so you set up your "lifestyle" to do that.* Whereas on the go fast, you just throttle up and point the nose and sit there ans watch out for stuff.*


90% of the fun going by boat is the boat ride, every time I go some place and get tied up my next step is to jump in the dinghy and go for another boat ride!


Probably the most poignant quote ever on Trawlerforum!!!!!!!!

Always remember:

Boating is the art of going nowhere slowly and at great expense.

"To me, getting there is not half the fun."

That's why they charter tiny jets, or limo's.

If you want to GO somewhere a boat is usually a poor choice of transportation.

If you want to BE somewhere a boat is a great tool.

When I step onto my boat, I'm already where I want to be. (paraphrasing somebody)

"Cruising is the most expensive way to go third class"

"Cruising is the most expensive way to go third class"

Not on my boat!

FF

Hi, A dock buddy of mine is having a difficult time selling a 36 Grand Banks with a single Ford* (I suspect 120HP) They belive that the 10000 hours repells buyers--Anyhow they want to repower and create a 10-12 knot boat. Beyond the associated issues of Air volume. shaft and prop size, trans ratio-(silk purse out of sows ear) can you make a GB36 do 12 knots without pushing it down a mineshaft-Engine HP Required? 300ish? Anyone done this?

While one or two Ford Lehman 120s were the typical standard power for GB36s in the 60s and 70s, boats made in the 80s and 90s typically had more powerful engines. The most powerful engine I'm aware of that the manufacturer installed in the GB36 was the Cummins 210 (single or twin). However there may have been larger engines used.

The GB semi-planing hull is capable of being driven pretty fast through the water--- with a pair of Cat 400-plus hp engines the GB42 can cruise at 14 or 15 knots. So the GB36 hull could be driven at 10-12 knots. HOWEVER.... the fuel consumption will be staggering. The GB42 with a pair of Cat engines burns about 8 gph at about 9 knots. At 14 knots or so the fuel consumption is about 25 gph.

Given the price of diesel these days and even higher prices in the future, more and more emphasis is being put on economy, not speed. The folks who have the money to afford speed aren't going to want a "little" boat like a GB36 anyway, so re-powering the boat with a fuel-sucking engine will simply shut if off from its potential market, which is economy-minded boaters. One of the largest blocks of GB buyers are sailboat owners who have decided that the demands of a sailboat, restrictive interior space, etc. is something they don't want to deal with anymore. But they don't want to give up the economy they enjoyed with a sailboat, and cruising at 8 kntos or so is just fine with them. A GB36 with a high fuel-burn engine will not appeal to this segment of the market at all.

Right now the market for almost all boats (except big yachts) is way down. The kind of people who would normally be interested in an older GB36 are simply not buying right now. They've got other financial problems to deal with. All the sales activity in our large marina is in big expensive boats.

I believe your friend would be far better off by repowering the boat with a similar engine to what's in it now. American Diesel sells a drop-in replacement for the FL120. Same engine mounts, everything. I believe it's a 150 ph engine. Northern Lights/Lugger make a nice 6-cylinder diesel, also of about 150 hp, that would be a good replacement. John Deere makes a nice engine to replace the Lehman 120. And there is the Cummins 210 (or maybe it's 220 by now). All of these engines except the one from American Diesel will require the engine and transmission mounting system to be modified but since all these engines have been used in the GB36, the modification work should not be difficult or overly expensive. And all these engines are straight-sixes, so will not make the engine space overly crowded.

I believe your friend would be far better off by repowering the boat with a similar engine to what's in it now.

If -8K efficiency is the goal the smaller 4 cyl Deere would be my choice.

Same shaft ., prop and if its a TD keep the tranny.

FF

Thanks for the replys--It was not a question about fuel sucking-some people choose to suck fuel (still cheaper than therapy or lawyers per hour) but rather-how to choose an engine that will push an exsisting/owned hull past feeble to feeble plus.

My own opinion is that 10,000 hours is not that much-keep the ford, enjoy 7 knots. Second, going from 120hp to 150hp is not going to do 12 knots. and if you must repower a GB36 to do 12 knots-why not try to achieve plane?
300hp and trim tabs/20 knots-better than pushing a wall of water in front of the bow. Semi-displacement is like ED, we are looking for the viagra that will do that. Perhaps 300hp Yanmar, 2/1 tranny, 2 inch shaft, bigger air intakes, and what else--that sort of thing.

Pushing a hull faster will always result in decreased fuel efficiency. If 8 knots is deemed "feeble" and 10 knots is considered "feeble-plus" there is no free lunch. You will use a significantly greater amount of fuel to run at even 2 knots greater cruise speed.


The GB36 hull will never truly plane unless you install many, many hundreds of horsepower in it. 300 won't do it. 1,000 might. 300 hp will put the boat on a "sort of" plane--- mush through the water with the hull being partially supported by hydrodynamic lift. But with the typical engines installed in these hulls they will at best "semi-plane" (hence the designation of this hull type).

With our two FL120s, at 1600 rpm the boat does about 8 knots and burns about 5 gph (total) in the process. At full throttle--- 2,500 rpm--- the boat just about gets to 10 knots and Lord knows how much fuel is going through the engines at that point. The transmissions commonly used with the FL120, by the way, are 2:1. Actually 1.91:1 on one side and 2.10:1 on the other side.

The Ford Lehman 120 is said by the experts in this engine to be a 12,000 to 14,000 hour engine in marine use IF the engines have been operated in accordance to the era in which they were designed (1950s) and if they have received the proper maintenance required by this engine. Were I in the market for a GB with FL120 engines and if the engines in a boat I looked at had 10,000 hours on them I would regard them as getting into "needing a complete overhaul" territory. Particularly if I had no idea of the operation and service history of the engines. So in this regard I think your friends are probably justified in thinking the high time on the engine they have now is a deterrent to some buyers, particularly since there are so many other GBs out there with far less time on their engines.

That's not to say the engine will fail tomorrow. It may have several thousand hours left on the basic engine. But to a typical recreational boat buyer, 10,000 hours on any engine (except maybe a Detroit ) is viewed as a high-time engine. I know I would not buy a recreational trawler with this many hours on the engine(s) unless the price was adjusted to enable me to afford a complete overhaul which I would figure was not too far off in the future.

The GB36 question is anwsered-from my perspective, it was a mistake and I don't need to be involved.
*
MY Trawler at 43lwl, bulb bow, round ass, hard chine*and* at an s/l of 1.2* and a pc of .55 with 2.85 gears pushing a 34 inch prop at 1400rpm*(the torque peak)is achieving 7.5knots with a deere 4045d tier2-about a gallon an hour. Most other boats are fuelish in comparison.

Thanks for all your help!

As a comparison our Navy Launch hull is close to 49 on the water 3-1 gear 32 x 32 prop 1300rpm and does 2.5 to 2.8 gph at the same speed, with a 6-71 de- powered to 180hp with H60 injectors .

New engines do better! The Deere probably cranks 18hp per gallon if natural and 20 hp gal if turboed.

The 6-71 will only make 16 hp/gal.

-- Edited by FF at 04:54, 2008-10-07