Catamaran keel feet / shoes

[Dwayne Lister]

I seem to remember that Prouts used a GRP bonding paste, but personally I would use something like 5200 or a poly-sulphide. That way the joint has a bit of give / flex but is still plenty strong.

The Prout shoes were hardwood in order to allow then to absorb a degree of shock and point load from stones etc without excessive damage. They were intended to be sacrificial and to wear if the vessel was grounded frequently or kept on a drying berth.

Regards

Dwayne

[UNCIVILIZED]

There are several of Richard Woods's designs that have wooden skid strips/sacraficial keels. Including on a few of his boats which have daggerboards as well. Which, one of the latter has hardwood sacrificial keels bonded in place with Sikaflex. And she fully went over a reef with them, though there was some damage to the outer skins of her hulls.
IIRC they're about 3"x3' oak simply glue in place with Sikaflex.

What materials you use really boils down to how much money you want to spend, how much effort you want to put into mounting them, & how much extra drag you're willing to add to the boat. As FWIW you could even use some copper plate attached with bolts that you epoxy bond into the current keels. Copper being a lot easier to form than stainless, & obviously it shouldn't foul much with marine growth.

I don't know how flat, or curved the undersides of the current keels are, but another option is to either beef up the laminate down there by 10-15mm. Or bond on some G-10 or FRP plate, along with a bit of laminate to help affix it in place, & smooth out the joint where it meets the keels.
Simple to do, low cost, tough, low drag, adds to the structure of keels/hull in terms of strength.

[valhalla360]

Google keel guards.

They are rubber pieces designed more for small go fast boats but should do the trick and be simple to install.

[CatNewBee]

I am looking for the same thing for a Lagoon 400.

I saw recently a L400 on the dry with a small keel damage in the front section,
where the gel coat is splintered away and the fibres of the fiberglass are exposed to the salt water. The keel was soaked and dripping for days. it seems the boat has hit a small metal buoy and the gel coat was just gone on this spot. A keel shoe of metal as shown in the video would have prevented the damage. A wooden shoe on the bottom would not have helped, because the hit was on the front lower edge, it is only good for beaching the boat.

A good protection should cover the front part and the bottom of the keel.

I hope somebody could produce this parts, they can be easily glued on with Sika to the keel. I would not bolt them on.

[Captain Bill]

Did either of you who were looking to add shoes actually do so and if so what did you do? Also how has it worked for you?


I have found that the canal system leading to my house has a number of unmarked rocks that are really only a problem for me at lower tide levels. So far I have found two of them the hard way. I have the option of not going out at lower tide levels and avail myself of this option. The problem is I don't always have this option coming back as sometimes we don't have a daylight high tide here in the Gulf of Mexico in the winter and I need light to avoid the rocks I have already found. One of the rocks I actually found within five minutes of high tide though there was a strong north wind which tends to blow water out of our canal system. That was also the highest water level we had for the next three days. But I digress. Fortunately my keels have crush compartments bow and stern and slope downward towards the stern. The keel bottoms are flat so it should be easy enough to attach some sort of shoe. The downward slope of the keels works to my advantage in that the damage so far has been limited to the aft 2 feet of the keel. I'm debating with myself over using G10 epoxy sheet, a hardwood, or a stainless shoe. To spread the load I am thinking I will cover the entire bottom of the keel no matter what material I ultimately choose. Anything you can share will be helpful.

[Sos]

We have Iroko hardwood planks (about 30mm thick) bonded to the bottom of our keels. Stuck on with a product called CT1 - not sure if this is just a UK product?.
We criss crossed the timber using a skill saw set to about 3mm depth and then drilled countersunk holes in between to help with adhesion.
Our marina drys to mud so lots of catamarans have these added to their keels.

[Shaneesprit]

I would think that wood adds buoyancy and stainless adds weight.
Mine has a wood and this is fibreglassed on and the fibreglass is then sacrificial. Although that takes care of the bottom.
If you’re going to want to protect the leading edge (if that’s what you are describing) then I think you would need to start by making a mould. Before deciding what material to use.