Vintage full displacement hulls?
Hi guys,
I am tempted by a slightly bigger boat for economical liveaboard cruising instead of the shorter trips imposed by a smaller unit. Spurts at planing speed are great for short jaunts, but in longer trips range (=fuel economy) would be my main priority. I realize that much of this comes from engine choice, ie slow turning diesel with small injectors and modest horsepower ratings to run them warm at low cruise speeds.
But half of the equation is in the water, ie an efficiently shaped hull. Not knowing much about hulls, I thought that a semi-displacement modded V-hull flattened at the stern could work also as a displacement hull, when cruising slowly. But it appears that hull shape makes a considerable difference in terms of drag and fuel economy. To get the longest possible a cruising range would require a hull that was designed exclusively for displacement speeds.
How would you rate Hatteras displacement hulls? I know Hatties are famous for their great ride on plane, but I wonder if it is the definitive LRC? :confused:
Also, would you know which of the earlier hulls from the early sixties (first factory location rounded porthole designs) were built as Long Range Cruisers? Maybe its a generational thing, but I feel more connected to the earlier units that remind me of days forgone: I yearn to live aboard a Hatteras "time capsule".
For example, would a 1965 41' Double Cabin be an LRC or does it have the same hull shape as my 34DC? And am I wrong in thinking that an early 50' MY would have a slow full displacement hull? Are the only true displacement Hatteras LRCs more recent production boats than the first run of Hargraves?
Thanks in advance for setting me straight! :)
Rich
Re: Vintage full displacement hulls?
The only Hatteras LRC's are labelled as such and none were made in the 1960's. The LRC's were 42,48, and 58 footers with Detroit Diesels starting in the 1970's. The smaller boats had 53 series, the 48 58 footer 71 series engines. A true displacement hull is pretty well rounded along it's length and they tend to roll. How the Hatt LRC's compare with other full displacement hulls, like Seaton designs, I don't know. Many "full displacement" hulls are not that at all with flat bottoms aft and the ability to plane with gigher HP packages such as some Marine Traders and Grand Banks.
As you have perhaps read here, many planning Hatts get about a mile per gallon at 8 to 10 knots with engines running at low to moderate RPM. While not ideally suited to true long range displacement cruising, they do offer good value. For true long range efficient cruising it's hard to go above six or seven knots without reducing MPG.
The single most important factor in evaluating how important MPG efficiency is to you is to judge how many miles (or hours) you'll run annually and for how many years. At a few hundred annual running hours, the difference in fuel cost between 1 and 2 MPG is not significant; If you want to cross the Pacific and cruise extensively, say a thousand hours or more annually, range and efficiency becomes critical. Some trawlers exceed 3 NMPG but only at very modest speeds, often around six knots or so.
You might try David Pascoe's website and see what information he has on different trawler designs. You can also try sites like MTOA (for Marine Traders), search for Steve Seaton designs, and other name brand trawlers such a Nordhaven. A bulbous bow may be a design feature that can improve some hull designs but it's more trouble than it's worth for most of us. You can also post questions about efficiency on Trawlers and Trawlering a message board with about 1700 trawler owners...several from this list post there, including myself.
I may be wrong, but most often when I see high NMPG claims I see very modest speeds rather than super efficient hull design. An extremely efficient design needs to be narrow and that's not seen in trawler design.
Re: Vintage full displacement hulls?
Hi
I was looking at Hatteras LRC for fuel economy as well. I ended up purchasing a 48MY series 1. It is on what Hatteras calls a dual mode hull, rounded at the front and flattens at the keel for either diplacement running or planing. The one I found was equipped with Niads. You can go to Sams and read the review on this model from when it was introduced. So far I am really happy with this boat and a glad I chose it over the LRC's. It has a little more room than the trawlers and has the option of 16-17 knots if needed.
Chris
Vintage Hatteras hulls vs. LRCs
Hi Robin,
Thanks for setting the record straight - I understand that Hargrave meant to provide a stout and fast hull for Cape Hatteras passages during storms, not for eeking away at fuel scan rates.
I was dreaming of an altogether too pricey early 50' MY, but am now looking at cheaper 41' Aft Cabins of the same vintage. It would be for cruising the Med, so the smaller the size the lesser the prohibitive docking/tax/insurance not to mention fuel skirting $7/gallon.
I guess that for the relatively limited distances in the Med, from Greece to Spain, the fuel usage difference between narrow full displacement hulls and that of an early 41 or 50 foot Hatteras wouldn't make it worth the other compromises involved.
With a pair of 6 or 8 -53's run at 8kts it would probably cost around ten bucks per nautical mile, genset included. Plus the extra built-in safety of higher planing speeds could come in handy to evade the rare nasty storms. I had earlier looked at older (and bigger) full displacement yachts and found them to be closer to one liter per kilometer, or as you said, approximately 3kts per Gallon. I had hoped remaining closer than farther to those numbers with a smaller boat, understanding that for equivalent economy the hull speed would be proportionately slower.
Would you suggest I renounce my almost exclusive attachment to the earlier series of Hatteras in order to get one with a more efficient hull (an LRC), or would a sixties 41' Aft Cabin or 50' MY have a hull close enough in terms of slow speed economy to the LRCs?
Thanks for your helpful explanations,
Rich
Differences in Hatteras MY Hulls - Hargrave era to now
Hi Chris,
You are lucky indeed to have found one already equipped with stabilizers! :cool:
Your 48MY is a great deal more recent than what I am looking for, partly also due to pricing of more recent units, it is almost a generation younger than the candidates I am considering. Would its more recent hull provide any economy/stability/seaworthiness advantages over the early Hargrave hulls? I figure that it may be a bit more efficient in high speed use versus in slow poke mode. Have you heard different?
THX,
Rich
Re: Vintage full displacement hulls?
A few 48 Series I MYs were built as displacement-speed vessels with smaller engines and not intended to plane. If you could find one it would be a good boat for you.
The LRCs are very efficient displacement hulls and run inexpensively at 6-7 kts. Many have stabilizers. They are not cheap- they are usually well kept up and the price reflects the condition.
41MYs are well-built heavy boats that were usually powered with gas V8s or 53 Series Detroits. What might suit your needs is to buy a 41MY or TC and repower it with modern smaller diesels, intending to run it as a displacement speed vessel. That has been done with some other Hatteras MYs and the owners seem to like what they have. You would also gain in that the engine room would be far easier to work in- the Detroits are very large. Any modern replacement would be quite a bit smaller.
Re: Vintage full displacement hulls?
there is a 43 my at my marina for sale that has 671n's think is stabilized. think this would make good alternative to trawler. think he is asking 180k
Re: Vintage full displacement hulls?
Rich
The 48MY series 1 hull was built as a dual mode hull, made for displacment or planing. It has rounded chines forward. The boat has kind of a trawler look profile. It runs very well a displacment speeds. The only thing is if you have the turbo engines like I do, you need to make sure you run at high enough rpm to keep the engine temperatures at 180 or so. On mine 1200 rpm is about 12 knots and 12 GPH, 180 degress engine temperature.
Chris
Re: Vintage full displacement hulls?
While you are at it, you may find two threads posted here at Sam's of interest:"Turbo vs NA efficiency" and "Single Engine Cruising". Use the search feature to find these.
The first concludes that turbo and natural engines seem to have about the same efficiency while the latter concludes that running twin engines at low RPM (but enough to keep temps up to normal) is about as efficient as running one of two engines at somewhat higher RPM.
The slower you cruise, absent opposing currents, the better your MPG. This becomes more realistic with smaller engines aimed at displacement rather than planing operation. But running bigger engines at moderate RPM achieves much of the improved efficiency.
I don't recall seeing any posts on Hatteras LRC MPG...Anybody have any actual data??
Re: Vintage full displacement hulls?
Speaking of nautical mpg, my son has a 1986 32' Hat with Cat 3208 engines at 300 hp. He was complaining about fuel consumption. I went to the brochure archives section on Sam's web site and found a page from the second magazine article that gives all this data for a 32 with Cats. I was shocked to find that, with the exception of 1000 rpm figures, all the nautical mpg were between .8 and 1.1. Actually, full thrittle yielded one of the better figures. I always thought that displacement would give the best nmpg. Not with the 32 Hat. She stays about the same throughout the rpm and speed range. Our gas engined 36C sure doesn't act like that.