Boat Lift

[Greg V]

Hi everyone. I'm a proud newer owner of a 2017 R29 and I am taking it from NYC to our new home in MD next week. Our new home has a boat lift and I need to know what dimensions to set the boat lift bunks. The boat is in the water and I will be taking the boat down to MD via the water so I obviously can't see the hull to measure.

I forwarded the drawing provided by RT to the boat lift company and they are asking for more information. The drawing provided only shows widths from outside of chines to outside of chines, not how high or wide the bunks need to be. Does anyone have any suggestions on how they should be set?

Thanks in advance.

Greg

 

[ALICE J]

Perhaps a boat trailer manufacturer could give you the dimensions. Float-on in Vero Beach makes trailers for Rangers as I have one for a 27. Just make sure that the thru-hull fittings clear the stringers.

 

[mjq1987]

We keep our boat on a lift, too. I don't remember the exact dimensions I used for the bunks/spacers, but I will measure tonight and post them. I can also post a couple of pictures for reference. You will need spacers under the bunks to keep the keel off the cradle beams and the cable loading and thru-hull locations are parts of the puzzle.

Our boats are heavy and the center of mass in the factory drawing is for a dry boat condition. We have a CB so your CM may be slightly different, but with the tanks loaded and normal gear onboard, our center of mass is about 18" aft of the dry center of mass (13,000 lbs. loaded vs. 10,800 lbs dry). That makes a big difference in cable loading and in where you should/can position the boat on the lift depending on its capacity.

Here's a link to a calculator that you can use to estimate cable loading and required positioning based on the boat's dimensions and weight: https://stokesmarine.com/load-lift-calculator. It's a good starting point, but it assumes uniform weight distribution throughout the boat's length and beam dimensions which is not the case. I ended up getting a cable tension gauge from Amazon (https://amazon.com/dp/B0038YY3W6/ref=tw ... UTF8&psc=1) to determine how I could position the boat bow in and stern in for maintenance, waxing, etc., and to figure out the exact cable loads in each setup. I may have overthought this, and I definitely over-engineered our lift (20k lb/6 pole lift), but I didn't want to take any chances.

 

[Matty]

I went through this a few months ago with our R27. Andrew at Ranger Tug provided drawings which the lift installer found to be very helpful. Based on the drawings and weight he was able to determine approximate center of gravity. Once on the lift they made adjustments based on cable tensions. Originally I was replacing a prior property owner 6,000 lb lift with a 10,000 lift thinking that was enough for the R27. Using a calculator as provided in the prior post I saw that going up to a 13,000 lb lift gave me a larger margin of error on center of gravity. Cost difference was about $1,200 so I made that last minute change and got a lot of peace of mind. I assume you have already confirmed the lift capacity.

As an aside - we needed to move two pilings as I was also changing the direction the lift was facing. Upon pulling the first one out we discovered a lot of damage from insects eating away at the wood. So had to replace all four but again I have peace of mind.

 

[Matty]

here is a link to post where mjq1987 easily convinced me to increase lift capacity.

viewtopic.php?f=5&t=12803&p=86586&hilit=boat+lift#p86582

 

[gwishon]

RT should be able to provide you with a drawing containing all the relevant dimensions. If not, I have them in an pdf that I can dig out for you when I get back home tomorrow. I do know that I had to install 20” risers below the bunks on the 16k lb. lift at my home. As far as the rest of the dimensions, they’re shown on the drawings.

 

[mjq1987]

Here are the lift setup specs I used:

Bunks: 4" x 10" x 14'
Bunk Spacers: 6.5" x 12"
Height from top of cradle to top of bunk: 16.5"
Distance between bunks: 36" center to center
Keel to cradle clearance: 2"
Distance from Multiport Thru-hull to end of stbd bunk: 12"
Distance from Engine Thru-hull to end of port bunk: 9"

With this setup, the generator thru-hull sits on the port bunk which I am okay with since it's a flat pickup. I considered increasing the spacer height and moving the bunks further apart, but that would have prevented me from putting the boat on the lift bow in when I needed to, so it was a trade off I was willing to make.

Here are some pics of our setup. Hope this helps.

 

[Matty]

Looks great. Only thing i suggest is my installer added a slight dip to stern so it would drain well in heavy rains.