bertram31.com

As fiberglass boats became "thinner" over the years (less glass) ... did Bertram ever change their layup schedule so that earlier "60s boats" would be different from late 70s or 80s boats ?
thanks

Yes they did but the exact layup change I'm not sure.

As the boats moved from the 60's to mid 70's the amount of glass in them was reduced; How much? I don't really know.

There was also a change to the lifting strakes at some point. I'm not sure if this coincided with the layup change or not.

This doesn't mean be afraid of the "newer" boats. They have a more efficient/drier strake layout and you can still drop them and not break them.

jp i am going to answer that " unknown layup thickness change" in the near future . i have a core sample from my 1973fbc and will cut a identical hole in a 1967fbc (tranducer).one fact that i can tell you is bringing the strakes all the way to the bow line does not help until boat exceeds 60mph .boat hits rollars in a headon sea and comes out of water the lenth of the hull.from this we can deduct stake change in 1969 or 70 was a good weight reducer the newer style stakes are the way to go in a 31bertram doing less than 60mph. i should think that includes 99% of us.

Bob,

boat hits rollars in a headon sea and comes out of water the lenth of the hull.from this we can deduct stake change in 1969 or 70 was a good weight reducer the newer style stakes

Here's a 67/B31...please show me the difference in the strakes that reduce weight? compared to the later models?

[img][img]http://i145.photobucket.com/albums/r210 ... 0011-1.jpg[/img][/img]

capt.dq i am in bad shape from accident. i can not get to boat but capt. patrick has old and new strake pattern in archives.

Bob- What happened? How are you? Do you need anything? Walter

walterk i am in a hell of alot of pain. i went from bad to worst .x-rays show no breaks but pain has spread to back .i cannot walk.been on drugs so long i am losing it!!!

Thanks Bob,

Hope you feel better soon.

R,
DQ

Dang Bob
I had no idea. Are you suffering from an old injury or have you had an accident recently?

Hope you get better soon.

At least you can get on the site here.......we will keep your spirits up

Harry

Bob, I'm just around the corner. You need help getting around or to run some errands, call me 678.8756 I know Brewster would help out but, you know, he's too busy stuffin' shrimp

soft tissue injury. caren had that for a few years after she was t-boned by a maserati. there are dr.s that specialize in treating them. caren went to a pain clinic in riverhead but i bet theres one near you...worth investigating.

thank you brothers two weeks ago in the early morning i hit black ice with truck skidded into 3' diameter tree .totaled the custom truck and put right knee under dashboard.all kinds of soft tissue damage also manage to twist lower back into prezel.i think those exploding air bags hurt more then the steering wheel.i had all kinds of reponse to those 160 outdrives for sale whomever is honest god bless you.you have capt. patrick address.

Bob if need anything buddy let me know. Me and Dick can come over and help you.

you guys are truly brothers in every sense of the word.the back is coming back the knee is another story.perhaps time heals all wounds .i will limp about working on the boat very slowly.i thank everybody for there concern!!

Take it slow Bob, don't push your luck. Walter

Bob- I'm right over here in West Islip. If you need help with something let me know.

Bob ... All the best from a Sag Harbor kid living in Lauderdale.

3' diameter tree...those do not have much give on impact. Glad you are still with us...bruised and banged up but with us.

I slid the front of my vette under a guard rail some years back, I was coming down a hill that had a patch of ice. Wheels finally got some traction the last few feet and she came to a stop before hitting the wall at the bottom just past the guard rail. The nose didn't touch the wall but since the lights where on and up, the passenger side caught the guard rail and ripped the glass nose apart on that side. That day sucked.

Hope you heal up soon...

CArl

Bob,

Sorry to hear your banged up. Just back on the board from a road trip. Leaving for Long Island Fri. pm to do a seminar Saturday. Hope you feel better.
TAKE IT SLOW.

i really am overwhelm with all this thoughtful consideration you guys are the best. i now walk with a cane and go to physical therapy ,doctors say iron horse days are no more .i shall concentrate on building bertrams without it i would go "off the wall".again i just want to thank all of you for you concern.-----------brother bob

Bob, Iron Horse is a state of mind, not body, those days will never be over until you are. Keep at it, do the therapy, attack it the way you attack everything else. I'm cheering for you.

Rod

Bob-If I know you, you'll start designing a "better cane" made from the newest, latest materials that will make you walk a few knots faster than with a stock cane. Walter

Strakes from a 1961, Hull #168:[img][img]http://i91.photobucket.com/albums/k293/ ... DII001.jpg[/img][/img]<a href="http://s91.photobucket.com/albums/k293/ ... -06277.jpg" target="_blank"><img></a>

Sorry for the two in a row, don't have the picture thing down. I can't say if the 61 is thicker or heavier, but it my testimony is that it is a little slower. Best as I can tell it is about 1 knot slower than similarly powered boats. I have Cummins 270's and there are several boats that I know the owners with the same props, trans, shafts, etc. At 2400 RPMs, 245 gals fuel, five fatsos, gear, ice, I am about 26 knots. (Funny thing is it seems the same when I am empty and by myself). Everyone with the newer strake set up goes about 27 knots at the same RPM. I'd like to hear if anyone has different results.

Here is one more view of the strakes in the water:[/img]

Is it conclusive that the strakes changed ? ... do we know when and how ? Did the change maybe effect the lift, thereby the speed ?
thanks

Okay my eyes are now crossed from going back and forth between those two pictures...

I've wondered about this as well... The pictures clearly illustrate the difference. Thanks guys.

On the older boat (1961), three sets of strakes run into the chine, with only the lowest one meeting itself on the foreward keel.

On the newer boat (1967), only two sets of the strakes terminate into the chine, whilst the two lower chines meet up on the forward keel.

I can see where the newer strake pattern would certainly add more lift to the lower, forward portion of the hull.

ok lets go real slow and take this subject from the begining. around 1938 the us built a plane that could land on water and take off even in rough water when rescue off a down pilot was needed.the plane was a pby and became very sucessful during WW2 .the plane had a unique set of floats that had " lifting strakes" to get the plane airbourne as quick as possible.low and behold ray hunt uses the same design on the new 31 bertram.the 1961 thru someware around 1966 bertram had the stakes go all the way to the bow above the chine line.this was not nesarsary in a boat going less than 50 mph.mainly effected re entry after boat left water and came back down.bertram eliminated this old design ( you have to look at both head on (at bow) to see the differance).next change came around 1973 mid year.they lighten the layup.you can see this by archimedes law.
a 1973 or newer 31 bert with a big block mercruiser and 50 gallons of gas will sit in the water with the reverse chine edge just out of the water.the same powerplant in the 1961 the edge is touching the water.this brings us to another problem the reverse chines must be in the water if you intent to drift while fishing .the (rldt) systrom comes from the chines being out of the water like when using a 4cyl powerplant. basicly the chines stop the boat from rocking in a beam sea.you need about 1000 lbs per side to put the chines in the water. needless to say cat 3208 or cummins 504 bury the chines by 2" or so making the 31 bertram the best it`s going to be at the cost of fuel economy and cruise speed.there is another discussion on top speed riding on the strake edges to reduce drag to a minimum but thats a whole new story.

The quickest ID is to count the number of lifting strakes that meet the chine. Earlier models will have three, later models will have two.

Near as I can tell, the strake design happened sometime in 1967. By flatening the bow upward sweep, the effectiveness of the lift at slower speeds was increased. Simply a slightly quicker and lower speed requirement to begin planning.

thank you capt. patrick; a picture is worth a thousand words for sure!!!

So which one is better?

well these pictures clarify my post.brew look at the old style and imagine the 31 bert flying out of the water.look closely at the old strakes and you can clearly see how on reentry the strakes would be more incline to push the bow up.at 50mph and above "stuffing the bow" becomes a major problem on a boat that in a perfect level plane.the new desigh is much more practical in helping the 31bert plane faster (fuel economy) and staying on plane with the same power plant at a lower rpm.for you brew it would help when higher speed trolling like tuna and wahoo.

Brewster Minton wrote:So which one is better?

Once on plane, it's a mote point. Behind the bow configuration, the strakes are the same. The older style may have some slight advantage cruising into a head sea, but the key word is "slight". Same goes for the "slight" increased lower speed planning efficency of the later design...

Another "slight" reason to be educated on the visual design differences, if you're looking to buy a B31, is that the tree point design instantly identifies the boat as an older heavier fiberglass layup. A desireable feature to some of us. '67 was the year that Dick Bertram sold out his share of the company and the bean counters started reducing the layup schedule. '73 saw the biggest reduction due to the oil embargo, but wasn't the first year of the move away from the battleship hulls of Dick's watch.

Thankyou .... that got to the question

Pat-

Thanks for the clarifcation. Still like my 73, but for the most part i baby it. Non the less, I will advise my friends to look at the older models for restoration.

DeNada is supposed to be a 1966 model........is it possible that she is actually a 67 ???

[img][img]http://i147.photobucket.com/albums/r289 ... G_1801.jpg[/img]

[img][img]http://i147.photobucket.com/albums/r289 ... G_1787.jpg[/img]

Harry[/img]

I stopped at the yard today and took a good look at the strakes on HMS Hound (old style) & Chimera (new style), which are side by side so easy to compare. It seems to me like the strakes on Chimera are thicker and have more area. This might account for the extra knot of speed, my theory is more lift down the whole hull.

john one other thing to keep in mind it takes torque to lift that bert on her strakes in your case that is meaniless (cummins 270) but a small block gasser or chrysler from old cost quite a bit of fuel economy overcomeing this lift .you are just fine with old strakes and 500 lbs of torque.

gplume i wanted to restore your confidents in the 73 bertram.this is a section from the deck had to install a new pipe hole above rope locker.check out this layup and stonger we could cut a path thru the ice to the north pole .the 73 31 bertram is the closest to a ice breaker that i have ever seen .i would definitly use 73 and up to restore.the deck is 15/8 " thick anymore would be ridiculous by todays standards.

I can't imagine that anyone has a question regarding the soundness of any of the manufactured B31 hulls.
The way the hulls were built leads to an extremely thick center line because of the 2 piece jig.
The fact that the lightest of the produced hulls has not failed is a tribute to Bertrams "right sized" layup.
We run a 1977 "light hull" this boat has taken regular poundings by us to and from the 100 mile mark in the Northeast. Not to mention the number of beatings it took in the gulf before we purchased her.
I cannot think of another hull ever produced that can be driven without failure like our beloved B31's.
The advantage to purchasing the late model hulls is apparent immediatly in the long term survivability of the hull (it didn't sink before you got it) and the upgrades in the finished material (no gel coat alligators)
To date our little boat has been able to survive above and beyond the call of its crew. There has never been a moment that I've felt insecure in this boats ability to get me home safely. There are very few boats that I've driven that are so highly rated.

Thanks to you guys I now find myself checking out the strakes on every hull that I see, bertram or not.

I now find myself checking out the strakes on every hull that I see, bertram or not.

It's a sickness, that I'm also quite afflicted with. All the other boats however, suffer strake envy.
I've noticed that all of the B20's & B25's have strakes very similar to the later style B31 strakes... So they (Bertram or Hunt) had that style around for quite a while before switching the B31's in '67. Unless there are some early B25's that I'm not aware of with smaller strakes, further up on the chines...

I've noticed that SeaVee has recently changed their strake pattern..... Used to be real similar to Contenders, which was really just a take off of the older Formula233. Now, the SeaVee has two strakes way up on the hull, just under the chine, with a noticeable bare "v" around the keel. I think the older SV hull looked like a much better design. Might have something to do with new ownership...

Guy's
After going thru my past survey report pictures the strake changes started in 1966. My 1961 Express has 3 strakes, Kahuna 1963 Sport Fish has 3 strakes, Zero Cavity a 1965 FBC has 3 strakes touching the chine at the bow. Sandy Bird a 1966 Express has only 2 strakes touching at chine, and all the others after 1966 have only 2 strakes. Harry, De Nada is more than than likely a 1966. Looks like Bertram changed the mold in early 1966, changes were made due to the number of hulls pulled from original mold, shrinkage, wear and design changes are all factors, they did manage to pull over 400 boats from the original split hull mold.

Bob-

Thanks for the heads up. Confidence restored. Still curious about the hull sample you said you were going to take comparing to an older model. Be looking for that update.

Where my boat is lots of Sea rays and Bay linners. My boat is known as the "battle wagen".

Hey Pete, how you doing?

Whats keeping you busy these days?