Mahogony anchor platform stock

[bcooke]

I was looking for some stock for a mahogony anchor platform locally and I found some but I can only get it in eight foot lengths. I think it was about 27 board feet for $250 plus tax. Is there anyone else that would want to split a plank with me? I am toying with the idea of using about four feet which would leave at least four feet for someone else. I could probably find other uses for the material eventually but if someone else was looking I would rather not have to store the extra.

I think the actuall dimensions was 8' x 12" x 2.75" S2S

Or does anyone have some stock they want to part with?

And while I am on the subject. My cousin has some white oak stock that he is trying to sell me and it is a lot cheaper than the mahogony. Any thoughts about using the oak instead? Is it just a cosmetic thing? Wouldn't the oak check a lot more?

-Britton

[JonnyBoats]

I would think the oak would be far more susceptible to rot than mahogany.

[bcooke]

I thought about the rot issue but I was thinking there is pretty good drainage in that application so it wouldn't be a big issue.

The more I think of it though, the more I want the mahogony. It is just an aesthetic issue. Mahogony looks better. My local boat crowd favor wooden boats with a ... shall we say... working boat patina. That is to say, paint and never varnish, lots of gray and buff colors, oak and pine being the choice woods to use (because this is New England and that is how New England boats are made...) I think peer pressure and the economic argument were making me think of oak as an alternative. But let's face it. A two inch thick old growth mahogony plank smoothly varnished off the nose would look much better. There really isn't an alternative except maybe teak and I am not that crazy :-)

-Britton

[Tim]

Don't use oak. Yuck. Leave the white oak for the workboats, and for wooden boat framing. It's hard to beat the look of nicely varnished mahogany, and it matches the other trim already on your boat.

One thing to consider is that an anchor platform made up of a single plank will be weaker than one made from laminated strips turned on end. Often, these laminated platforms are further strengthened with tierods running horizontally through the piece to reinforce the glue joints.

One benefit of this method is that you can use short thinner lengths of wood that might even be hanging around in your scrap box, rather than a single, expensive, thick plank. That said, if you end up buying the entire mahogany board, I am sure it will not go to waste as you continue working on your boat.

This is what happens to a mahogany anchor platform (built from two stacked, epoxied boards to make the appropriate thickness) when a mooring line wraps around the end of the anchor as the boat bounces over 4' waves during a storm in an unprotected mooring field. Any wooden platform might break under these cirtumstances. Be sure to take your permanent mooring facilities into consideration when building this sort of thing. (I hate my mooring field for this reason...)

[bcooke]

Yeah, I don't know what I was thinking when I started this thread. Of course mahogony is the only way to go. Silly me.

I remember reading the tribulations of your (Tim's) anchor platform as it was happening. Under the circumstances you experienced I don't suppose there is any wood that would not have failed. Maybe it is better that it failed rather than impose those loads on the deck structure? The stainless plate under the platform is a bullet proof idea but I really don't want to deal with it. Maybe it isn't that bad once you get into it but I can envision hours standing over a hot drill motor trying to get those holes cut. Just curious, what was the total thickness of the original platform?

I am thinking the laminating solution is the smart way to go but I feel like every wood project I have got into lately involves laminating and the simple "big board" solution is appealing to my lazy streak. How strong does this thing really need to be? I will have to think about whether the added strength of the laminations is needed in this application. I also need to visualize a 2.75 inch plank off the bow. It might look too big and crude.

And another question, why do so many glued up wooden anchor platforms have slots in them? Is it to shed water rather than funnel it back onto the deck or a weight issue or what?

-Britton

[Tim]

And another question, why do so many glued up wooden anchor platforms have slots in them? Is it to shed water rather than funnel it back onto the deck or a weight issue or what?

My guess is that not only does it save material, but it also provides surer footing when the platform is part of an actual bowsprit that one might walk over. Otherwise, I don't know.

The stainless plate under the platform is a bullet proof idea but I really don't want to deal with it. Maybe it isn't that bad once you get into it but I can envision hours standing over a hot drill motor trying to get those holes cut.

Drilling those holes was brutal. If I were doing it again, I'd mark the holes and have the welding shop cut them out with a torch, like they did for the opening over the stem casting.

Just curious, what was the total thickness of the original platform?

The original platform was made from two layers of 3/4" - 7/8" mahogany, for a total thickness of 1-1/2" - 1-3/4". The new platform features one layer of mahogany that is nearly 1" thick, plus the 3/8" SS plate.

How strong does this thing really need to be?

My solution with the plate was on the extreme side, given the failure of the original platform. Granted, the failure was under extreme circumstances. I feel that the original platform was strong enough for normal anchoring situations, and even slightly worse than normal.

Just remember that the stress on an overhanging anchor platform can be vertically downward if you're unlucky enough to be anchored in a very choppy place. Obviously, we try to avoid that, but depending on how you plan to use the boat, it pays to think through the worst-case scenario.

The solid plank will likely be more than adequate. 2.75" is mighty thick and strong.

[bcooke]

2.75" is mighty thick and strong.

Yeah, I thought so too. Probably too thick and will look out of proportion. I need to think about that. That plank was just calling me. "Buy me, shape me, love me..." I need to get out more often :-)

Thanks for the input.

-Britton

[A30_John]

Tim, this may be a little "off topic," but I was studying the picture of your broken anchor platform and wondering if your mooring pennant is a bridle or if you're using two pennants.

I'm having a new mooring built for my boat, and, like yours, it will be in an exposed mooring field. At this point, I've decided to go for a bridle, backed up by a second (smaller diameter) pennant left over from my old mooring. I'm curious to know what you've done there.

[Tim]

I have two full pendants, which is very common where we are. For this year, I have a brand-new pair of the high-strength Yale pendants that I will be installing. I would recommend this approach for your piece of mind--a small price to pay. I have a source for these pendants and can quote if desired.

If my boat were attached to the center of the earth with aircraft carrier anchor chain, I'd still worry.

The Yale pendants are excellent. There's a writeup in the Hamilton Marine catalog about them, including some great pictures of Wayne Hamilton's boat in a storm (secured with those Yales...)

[A30_John]

Thanks, Tim. I'll talk to my mooring guy again. I hope my boat never sees the same conditions Wayne Hamilton's pilot boat saw in that storm!

[dasein668]

If my boat were attached to the center of the earth with aircraft carrier anchor chain, I'd still worry.

If everything falls into place the way it should, I should be hanging on an 800lb mushroom with tackle sized for a 40 foot trawler this year. And I'll still worry.