bertram31.com

Hello all sorry for all the questions but i am very very thankful for you guys and this website. with that being said i am making engine beds like captain Patrick shows on here, my only question is where the new sisters are beveled and rest on the hull in the pictures should they get some kind of bedding between the sister and hull? similar to a bulkhead so theres no hard spot or is it close enough to the stringer where it doesnt matter? Also I am going to move the rudder ports so that the props can me removed does anyone know how far from center to move them? Thanks a lot everyone

I'd bed them in thickened epoxy (not polyester), but perhaps Bob Lico will have some advice.

Moving the rudder ports? Can you snap a few pictures of your setup, something sounds off.

Often the rudder is just off the side enough so the prop shaft can be slide in and out without dropping rudder, I wouldn't move rudder much further. There should be enough space between the shaft tip and rudder blade to remove and install props. How far does the prop hub sit from the Strut? The gap should be about 1/2 the shaft diameter.

Beefing up the strut pads as well?

Carl,

When I remove the shafts for inspection I absolutely have to drop the rudders...this requires some digging!

Carl I have always read that the stock location has to be moved for the prop to come off without dropping the rudder, if there is a way to get away without doing it im definitely game. Im going to cut the top off the supports and hopefully peel them off to replace the soaked wood inside and figured i would move them while im at it. here are a few pics sorry i dont have the prop and shaft in but i can if needed, i havent gotten the new shafts or props and still have to bore the stock struts
https://imgur.com/a/oR5O9L7
https://imgur.com/a/K1AZcCn
https://imgur.com/a/H817CVI

my engine mounts are illustrated in both Sounding and Motor Boating magazines ,both " got off " on the idea and displayed in the centerfold story. lets forget the exotic F-14 fighter parts and use all American bar stock products . aluminum stocks come in 21' long and 4" by 3" L shape . the distance from the main bulkhead to the fuel tank bulkhead is 48" so cut 4 pieces . the is the inside and top of the engine stringers . I used a 21' flat stock and continuous weld on each stringer to form a U bracket totally encapsulating the OEM fiberglass stringer. no need for epoxy or anything else just SS 1/2" thru bolts thru the aluminum U and stringer. Barry mounts sit directly on the top of the aluminum U . I used 1/2" stock but you can use 3/8" stock. you can make a jig of the cummins engine and ZF gears with 10 degree down angle out of a 4x4" wooden bean cut rear of beam 10 degrees and put 8" x 8" piece of wood directly to the end of beam this represents the gears . you mount a PRROPELLAR cooling directly to the center of that 12x10 piece the center of the propeller coupling is the center of your new F/G shaft log tube (I explain making this ) in past post. that just drop the engine in place perfect fit . never ,never let a marine mechanic on the boat !!!!!1 his entire theory will be different and your boat will rock and roll in addition with the center of gravity being 6" forward .

Yessir Bob, I have a couple Cummins blocks to measure I was just going to make a gearbox jig out of plywood. I was looking at the seaboard marine for the 220 dimensions. That is neat with the fighter jet stuff I have access to racecar and plane metals here in Sebring so I will look for that as well I already have the metal for the ramps and cap of the beds.

the bottom line !! the engine.gears sit as low and as far back as possible. the very back of the oil pan on the ZF gears should be no more than 3/8" off the bilge (at the gear oil removal plug and the ZF mount should be touching the fuel tank bulkhead . 31 Bertram is the driest boat on the water. the batteries (Odyssey ) sit in a battery box in the companion way . all weight down the centerline of the keel. fuel ,batteries, fresh water.

Dan

I remove my props without any issues and I have the larger rudders. We did not change the rudder ports, we left them right where they were from the factory.

I believe the shaft is the issue, and the rudders have to be dropped to get the shaft past them.

Yannis

On the 28, the distance between the shaft and the rudder does not allow you to pull the prop without dropping the rudder.

Bob I forgot to ask when the “U” that you create is done what is the width in the throat? I’m pretty sure I’m on the same page just trying to get it down. I appreciate it greatly.

Tony that is awesome to hear, saves me a ton of work. Thank you again and everyone else

the L shape aluminum is 4" wide from edge to edge on top, so minus 1/2" on inside and 4" flat stock welded to the opposite edge gives you 3" inside the L or you might say the stringer should be 3" thick in the engine compartment and this U slides right over it and then thru bolted in 4 places along the 4' length. the jig gives you the exact angle in which to make this L . there is a little tolerance in the Barry mounts to adjust exact angle to the shaft log, if you feel you have the ability I will go set by set the reduce the shaft angle .a couple of pages to make that post

I’ve been following the debate on the 6LP vs. the Cummins for a while, and honestly, both are solid picks for the 31, but it really comes down to how much you're willing to change under the waterline. I went with the 315 Yanmars because they’re higher revving and fit a bit easier without having to go crazy on the shaft size, I managed to stick with 1 3/8" shafts, which saved a lot of headache during the install. The boat cruises beautifully at about 24-25 knots, and while people say the Cummins has more low-end grunt, the Yanmars feel plenty punchy when you need to get up on plane. Just a heads up, though: no matter what anyone tells you, don't try to push these hulls past 32-33 knots unless you like the feeling of the boat trying to swap ends on you. Keep it simple, focus on the weight balance, and you'll have a great setup that won't break the bank on fuel.

Not sure how well you have the boat balanced, but we have had members who have passed that 32 knot limit with no problems.

Jimmy G's boat is probably the latest one, and of course, Bob Lilco who showed everyone how to do it.

The stern needs to sit lower in the lower than it did with the gas engines. Depending on your set up, that means moving the engines further back or making other changes to make it happen.

I know Bob lowered his engine and changed the shaft angle and if I remember correctly Jimmy did not.

If you want to go through doing all that work, and the juice is worth the squeeze for you that is fine, do it.

For me when we repowered, I wasn't looking to push that kind of speed, after all it is a 30 foot boat. Cruising 24 to 25 knots is just fine.

I agree. However, keep in mind that even the Yanmar 4LHA's, with just 240hp, can do the job just fine.

For example, my 28 cruises at 24-25 knots at 3000rpm easily and without hesitation, and if I remember correctly, Dug's 31 with the same motors does even better, probably thanks to the longer water line.

The law of "diminishing marginal utility" will dictate how much horsepower you will need...if the sacrifice (extra coin and effort) for that additional knot(s) is less than the extra pleasure, then go for it, if not, settle for what you have and be happy!

Running gear is an expense to be considered when repowering, without a doubt. Those are pricey items and often require someone experienced to do much of the work…and it can be lots of work.

The flip side is the running gear is a fixed cost, pay it once and you are past it. A larger long time cost is service and parts. When the local mechanic reaches the end of their knowledge and you need a factory tech, are they local, a few marinas away or are they driving several hours each way, on your dime. Are the parts stocked local or are you flying them in. Do parts come in a cardboard box left at your doorstep or require a Wells Fargo security vehicle with armed guards transferring ownership of parts to you.
Maybe a bit extreme, but compare turbo prices, injectors and maybe I’m not so far off.

All that said, Cummins and Yanmar are pretty much tried and true solid choices. Some models better than others, but solid proven motors. It makes a difference buying, installing, owning and when done selling. Sell a boat with Yanmars or Cummins check the box for many people looking for boats.