Boat lift bunks...

[juju151]

Does anyone know how far back the boat lift bunks need to be on a ProStar 190. My bunks stop about 1 foot from the back of the boat, so about a foot of the back of the boat is not supported.

The bunks go about a foot past the point where the rudder shaft comes out of the bottom of the boat. Is this going to be a problem? Just wanted to make sure before I leave it hanging like that. Thanks!!!

[east tx skier]

On the trailer, of course, they come all the way to the back. While general location (beneath the stringers) is an important concern, the important thing to remember is "how much surface area is in contact with the bunks. If memory serves, the owner's manual recommends 250 sq inches of surface area. So, if you've got that, you'll probably be fine. But I could easily be wrong. At times, we've accidentilly put my father-in-law's boat on the lift with about a foot hanging off the back. While it was fine, it wasn't long term. In other words, the next time we put it on, we made sure it was on.

[Davo]

It's fine... the engine would still be almost centered on the bunks anyway - a foot is nothing.

[88 PS190]

Remember to be careful where people walk, get two people standing on the overhang and you could get the boat to lift off.

[SKI*MC]

rough estimate for finding the surface area on te bunds would just be legth tims width times i think...

[east tx skier]

My trailer bunks are 12' long x 6" wide. That's 865 sq inches. So 250 appears to be a minimum number.

[SKI*MC]

mine is 12' long, and 4" wide which is about 576

[east tx skier]

Well, I think 250 sq in is what they've required since the 90s. So sounds like it ought to work.

[juju151]

Well, I think 250 sq in is what they've required since the 90s. So sounds like it ought to work.

Yeah my trailer bunks are like 2X6's laying flat "horizontal", so I was concerned about that with the lift...

My lift uses two 12ft 2X10's standing up "vertical" for the bunks...and on the bottom of my boat there is flat areas molded into the hull that are only about 3" wide that run about 3/4 of the length of the hull, which is where the trailer bunks sit. So I adjusted the lift bunks to sit exactly on those flat areas. The guy that built the boathouse said that I should move the bunks in so they are only about 2ft wide, but then it would be sitting on the curved "sloped" part of the hull, and I didn't like that idea. He doesn't have any experience with MC's or with boat lifts for that matter since I think this is only the 2nd one he's put in, so I don't know if his advise was very good.

But the motor is between the 2 I-beams that lift the boat...but not exactly between them. The very back of the engine cover is right over the rear I-beam. I'll try to get some pics posted tomorrow to see what ya'll think, just to be sure...I don't want to mess something up.

Thanks everyone!!!

[jimmer2880]

Yeah my trailer bunks are like 2X6's laying flat "horizontal", so I was concerned about that with the lift...

My lift uses two 12ft 2X10's standing up "vertical" for the bunks...and on the bottom of my boat there is flat areas molded into the hull that are only about 3" wide that run about 3/4 of the length of the hull, which is where the trailer bunks sit. So I adjusted the lift bunks to sit exactly on those flat areas. The guy that built the boathouse said that I should move the bunks in so they are only about 2ft wide, but then it would be sitting on the curved "sloped" part of the hull, and I didn't like that idea. He doesn't have any experience with MC's or with boat lifts for that matter since I think this is only the 2nd one he's put in, so I don't know if his advise was very good.

But the motor is between the 2 I-beams that lift the boat...but not exactly between them. The very back of the engine cover is right over the rear I-beam. I'll try to get some pics posted tomorrow to see what ya'll think, just to be sure...I don't want to mess something up.

Thanks everyone!!!

That's the way I've seen all the "overton's" style boat lifts.

[east tx skier]

I've seen lots of boat lifts like that. I'm leary of them all the same.

[jimmer2880]

I've seen lots of boat lifts like that. I'm leary of them all the same.

Absolutely, that's why my winter project this year is to modify my cradle to make the bunks more like my trailer bunks.

[Davo]

Me too...I'm not sure why they'd stand them vertical - when laid flat they "mold" somewhat to fit the curves in the hull.

JuJu just had his dock built too.

[gene dobies]

The reason for keeping them vertical and not flat is that is where their strength is. Laid flat they can support only a fraction of whan they can placed vertical. Physics

[east tx skier]

That makes sense. I would think 3 sets of support (angle irons like on the trailer) is somewhat essential if you go flat. Otherwise, you're going to have a large section of bunk in the middle that's bowed and not contacting the hull presumably.

[X-45]

I'd like to help JuJu but I can't take my eyes off your avatar. I sure there a question in there somewhere.

:cool:

[Davo]

LOL

Good point, Gene. I don't recall how many bunk supports there are on mine...I think 4 ea.

[BuoyChaser]

keep in mind the trailer bunks are designed to support the boat through turns, hill incline/decline and rapid stop/starts...

as long as you're supporting the greatest weight of the boat (engine) and keeping support bow/stern for when you're kids or drunk friend is jumpin' off the swim platform, the boat doesn't slide off with them...

BE VERY CAREFUL to not have the bunk resting on one of the hull ridges...the trailer bunks avoid this for a reason, this is a soft protuding piece of fiberglass, that will take 100% of pressure first...NOT A GOOD THING!!!

[east tx skier]

Even though movement isn't so much a factor, you want to mimic the trailer pretty closely on bunk location and amount of support. If you just support these bunks at the front in the back, they will bow in the middle and may not be in contact from the boat. At least that was what I saw the first time I walked underneath my father-in-law's boat when it was on the lift.

Even though you only need 250 sq in of surface area, my manual says the supports should extend from the chine to the keel with no gaps between the hull and the cradle supports.

[juju151]

should extend from the chine to the keel

Ok...help me out here, I've never been in the Navy. ;) Chine? Keel? I know bow and stern but that's about where my boat lingo stops. Here's a couple of pics that may help out...Thanks ETS, but sorry I didn't understand, you know how ignorant us boarders can be...especially us redneck boarders! :o

I've got both bunks set just inside that ridge there where the trailer bunks ride...

[juju151]

Here's another...

[juju151]

and another...

[juju151]

and another...

Do you think I need to double them up or do something else that would help? I can't move the boat any farther forward without doing some major modifications to the boat house with was just finished. But I don't want to mess up my hull...

[juju151]

Ok...one last one. The bunks extend 3ft past that rear I-beam that I've got the arrow pointing at...

[H20skeefreek]

I personally would at least extend the bunk to the back of the hull. I've seen lots of scenarios where a short bunk has pushed into the hull, I would take the bunk all the way back.

I would probably also put a taller bunk on the outside of the "ridge" (chine) to give support on that flat portion of the hull. some support inside might not hurt either. you are talkin' a couple of buck in wood compared to the value of your boat (even though it's a '98 "beacher".)

[jimmer2880]

Your bunks have more coverage than mine have for the past 5 years. If you do anything - I'd follow H20's recommendation of extending the bunks back to the back of the boat. But, not sure if you need to.

My cradle is a custom one & it has 3 sets of supports (6 total). It actually has less distance between the supports than my trailer does. And - I need to paint it this year & will be doing some other small mod's to it, so I figured I"d change the orientation of my bunks to better fit the hull, that's all.

[jimmer2880]

Juju - that's a sweet boat you have. Nice dock also.

[juju151]

you are talkin' a couple of buck in wood compared to the value of your boat (even though it's a '98 "beacher".)

Hey!...ain't I supposed to get some shampoo or something first???

I still haven't heard the shampoo story yet, but I hear it mentioned every time someone refers to the '98 "Beachers" :D

[east tx skier]

I believe the chine is the back part of the underside of the boat. The keel is the vee (or deep vee) where it goes from flat to pointy in the front.

This is just me. I would look at your trailer (or comparable trailer and mimic it exactly. If you're not good with metalwork, I'd hire someone to come out and attach some angled elbow supports. On the trailers the wood twists to support the hull as it slants toward the keel. You're not getting contact much past the center section front or back.

There's a perfectly good chance that your setup is fine for long term storage and that you'll never have any damage. I'm just saying what I would do if it were my boat. I'm a worrier and always remember the statement in the manual that "load damage can occur with as little as 15 lbs per square inch of pressure."

This is my father-in-law's setup, which was meant to mimic the trailer. The bunks are longer (because there's no v-bunk in the front. I sincerely doubt the twist is identical to the trailer, but oh well. Were it mine, I'd have extra support in the center as his bunks sag a little bit. I'm working on that.

[juju151]

Thanks Jimmer...

and thanks to you too ETS for the info...and the picture...

This weekend I think I'm going to get a couple more 2X10's possibly 16 feet long instead of 12 feet long, and put them right next to the ones I have there to double the width of contact on the hull...and possible try to make a small center V support like the trailer has up on the keel. Just to be sure...never hurts to overbuild or to be double sure.

[JDK]

I've got both bunks set just inside that ridge there where the trailer bunks ride...

From the pic. in this post, it looks like you've got the bunk boards set a little too wide to be right under the main stringers (which is the best place for them). Lift your engine box and look at the long black boxes that look like they are glassed into the hull with the engine mounts bolted into sides of them. Ideally, you want each bunk to be right under the middle of each of these boxes.
On my PS205, the inside edges of the stingers are 22" apart (for sure), and the stingers are ~10" wide(from memory). This means your bunks need to be 32" apart to fall right under the middle of the stringers.
If I were you, I'd narrow up the bunks to 32" on center (and doubling them up is a good idea too)....... then cut the top edge (lengthwise) to the same angle as the "V" in your hull.
I converted my sling lift to a bunk lift this summer, and I thought that having the bunks this close together would make the boat unstable (tippy) when climbing in and out while in the air. I was wrong, it is dead solid. :)
BTW, the "250 sq. in". and "support between the boat keel and chines" being referenced in the owners manual is where they are talking about lifting the boat with slings and not bunks. I believe there is also a reference to using a spreader bar to avoid damage too.

[RobertT]

I went the opposite way. Rather than try to have an absolutely stiff bunk, I have 2x8s "on the flat" so to speak.

They do bow down under a load, but that also makes the bunks perfectly conform to hull shape the entire length of the boat.

In my opinion, the idea is to have the least possible amount of force at the highest point load. Any time you have a curved structure being supported by a rigid support you will have high point loads, which is not ideal.

Looking at the pictures shown, my first instinct would be to actually scribe the contour of the boat onto the existing 2x10 that you have vertically. Cut the curve where needed with any saw, even a plain circular saw would work fine.

I would then take a longer 2x4 and attach it like a T to the top of the existing bunk that you just cut. I would use a waterproof glue and stainless deck screws. Then, I would simply cover it with cheap bunk carpet. The entire job should take less than an hour, and you would have a custom setup that is supporting your boat the entire length of the bunks. In addition, and probably most importantly, you will be over doubling the contact area.

Just a few rambling thoughts.

[east tx skier]

Bunk bow is good, unless it bows so much that it loses contact with the hull (what I noticed on my relative's bunks). I understand what you're saying though, but just feel I should clarify a few of my previous posts.

According to the manual, nothing supports these boats better than the trailer. Thus, the trailer, in my opinion, is the best guide for how to construct the lift cradle.

On the trailer, the angle iron supports go from 0 degrees at the back to an inward negative 15 degree angle (approximate) at the keel. The middle angle irons are somewhere in between. The supports move toward the centerline as well. The weight of teh boat takes care of the curvature in between supports.

[VTJC]

When I setup my new to me lift this spring I replaced the broken 2x8’s by doubling them up, since like most lifts they are only supported in two places the two boards per side decrease the deflection away from the hull and in my opinion support it better. I also angle them in a V having the bow mounts closer together than the stems, trying to match trailer as best I can. Creating a satisfactory compromise, between complexity, cost and support. Jamie

[juju151]

Dang!!!...it looks like I've got some major work to do tomorrow!!! And, wouldn't you know it, there is a cold front coming in tonight...so I'm sure the water is going to feel quite chilly tomorrow as well!!! :eek:

I guess I'll have to double up the wetsuits and hold on to the nads!!! :rolleyes:

[east tx skier]

I hear you. Our water level is down so much that we had to dig out under our lift to get the boat off. With such a low water level, the water cools off quickly.

[VTJC]

Not sure those of you from GA and TX should be complaining about the cold.

E.Texas when I was in Texas helping out after Rita, with an ambulance from VT (http://www.mrvas.org) , the temps were over 100 some days. One day the forecast was for high 80’s and the radio personality said it was starting to feel like fall, we don’t say that until we are skiing on a 50 degree evening.

We had a frost last night and are meeting to remove docks, lifts and course this afternoon its sunny but only high 40’s for air temp.

[east tx skier]

Yeah, it's all relative. You guys get to see the seasons change for sure. Plus, the closer to the Gulf you get, the more humidity plays a hand in what it feels like outside. In August, 80 degrees sounds like a dream.